Okay, listen up, because these are not your average brownies. If you’ve ever spent an evening torn between making a pan of ultra-fudgy, dark chocolate brownies and a batch of those chunky, peanut-butter-filled, candy-studded monster cookies, I have solved your life’s biggest baking dilemma. Why choose when you can have both? Seriously, monster cookie bars are fantastic, but put them into a pure, gooey brownie format? *Chef’s kiss*.
This recipe is pure, unadulterated joy baked into a square. We are talking about the creamiest peanut butter swirl, the satisfying chew from the rolled oats, and those bright pops of color from the M&M’s, all suspended in the richest, densest chocolate base you can imagine. I’m convinced these **Monster Cookie Fudgy Brownies** are what dreams are made of. I make these when I want to impress, or frankly, when I just want to eat my feelings, but in a much more delicious, textural way.
My favorite part about this cross-over masterpiece is that the oats and peanut butter actually help keep the brownies from drying out. It’s genius, really! So stop thinking about it and grab your biggest mixing bowl. We are about to make magic happen, and trust me, you won’t want to share these.
Why You Need These Monster Cookie Fudgy Brownies
Honestly, you need this recipe because life is too short for plain, boring brownies. This creation is famous around my house because it ticks every single box. Forget everything you thought you knew about simple chocolate squares; these are an event!
Here’s the lowdown on why you should drop everything and start your oven right now:
- Supreme Texture Combo: We nail that perfect combination—the super fudgy center you usually only get in a molten lava cake, but with the satisfying chewiness from the oats clinging to the edges. It’s chewy *and* gooey!
- Flavor Bomb: You get that deep, dark chocolate running head-to-head with salty, creamy peanut butter, all punctuated by candy bursts. It’s the most complex flavor profile in one simple pan. You can see how we tackle similar flavor layering in my popular cookie dough dip, just in bar form!
- Easy Peasy Prep: Despite sounding complex, these are beginner-friendly. Mix the wet, whisk in the dry, stir everything else in, and you are DONE. It’s less fuss than making separate cookies and brownies, which is why it’s one of my favorite easy bar recipes for quick treats.
Gathering Ingredients for Monster Cookie Fudgy Brownies
The structure of these **Monster Cookie Fudgy Brownies** relies heavily on getting the measurements perfect, especially when mixing that chocolate base with the chunky cookie elements. Don’t even think about grabbing substitutes for the key players here; your texture depends on it!
Here’s what you need to gather. I’ve learned trying to eyeball things when it comes to fudgy brownies just ends in tragedy, so measure everything right:
- You absolutely need 1 cup of lovely, unsalted butter, and it needs to be melted down first.
- For the sweetness backbone, get 1 1/2 cups of regular granulated sugar and a full cup of packed brown sugar. That brown sugar is crucial—it holds onto the moisture, giving us that signature chew!
- Four big eggs are non-negotiable for structure, plus a teaspoon of good vanilla extract to boost the chocolate flavor.
- Cocoa powder needs to be unsweetened, and we’re using 3/4 cup of it. Make sure it’s good quality; that’s where your deep chocolate flavor comes from.
- The structure needs 1 cup of all-purpose flour and just a half teaspoon of salt to balance all that sweetness.
- Now for the fun part that makes these *Monster* cookies! You want 1/2 cup of creamy peanut butter—I stick to creamy because crunchy throws off the batter consistency too much.
- We need 1 cup of rolled oats for chewiness. Make sure these are the standard rolled oats, not the instant kind!
- Finally, the mix-ins: 1 cup of semi-sweet chocolate chips (because brown is good, but more chocolate is better) and 1 full cup of colorful M&M’s candies. You can check out some of my thoughts on different peanut butter preparations over here if you’re feeling experimental with your spreads in these peanut butter cookie variations, but for the brownies, keep it simple and creamy.
Essential Equipment for Perfect Monster Cookie Fudgy Brownies
You don’t need a million fancy gadgets for these squares, which I love because it means you can whip them up anytime! Having these few items ready makes the process smooth sailing. Trust me, having the right pan setup is half the battle for clean cutting!
Make sure you have these items on your counter before you even think about melting the butter:
- A large, sturdy mixing bowl. Don’t try to cram this all into a standard one; you’ll end up wearing half the ingredients!
- Your primary tools will be a reliable whisk for the wet stuff and a sturdy spatula for folding everything else in gently.
- The pan choice is key: a 9×13 inch baking pan is what this recipe is built for.
- And please, please, please—parchment paper! You need that overhang so you can lift the whole glorious slab out once it cools down.
Step-by-Step Instructions for Monster Cookie Fudgy Brownies
Okay, buckle up! Getting these **Monster Cookie Fudgy Brownies** right is all about the order of operations. Following these steps means you get that deep, fudgy base and the perfect distribution of all those chunky mix-ins. If you follow them closely, you’ll have the best chewy, chocolatey bars ever. Trust me on the cooling step, though—it’s torture, but it’s necessary!
Preparing the Pan and Oven
First things first, we need heat! Get your oven preheating to 350 degrees F (that’s 175 degrees C if you’re using Celsius). Next, grab your 9×13 inch baking pan. This step is hugely important: line it completely with parchment paper, but leave a good overhang hanging over two of the sides. This parchment sling is going to be your best friend later when you try to lift these behemoths out without breaking them. We can all agree that a ruined pan of brownies is heartbreaking, so don’t skip that overhang!
Mixing the Wet Ingredients for Monster Cookie Fudgy Brownies
In your large mixing bowl, pour in the cup of melted butter. Then, whisk in both sugars—the granulated and the packed brown sugar—until everything looks smooth and glossy. It should look like liquid silk. Now, one by one, beat in those four large eggs, making sure each one is fully incorporated before adding the next. A little splash of vanilla extract goes in here too, just to give everything a nice aroma as it warms up.
Incorporating Dry Ingredients and Mix-Ins
This is where you need the gentle touch! Whisk in your cocoa powder and the flour until they are *just* combined. I mean it—stop mixing the second you don’t see white flour streaks anymore. Overmixing those dry ingredients activates the gluten and turns your beautiful, fudgy batter into something tough. Oops! Then, switch to your spatula. Stir in the salt, the peanut butter, the rolled oats, and all those glorious chocolate chips. Finally, you gently fold in the M&M’s candies. You want them distributed evenly, but you don’t want to smash them all up while mixing. We want happy, whole candies in our squares!
This mix of ingredients gives you the best center. If you’re looking for a few more ways to use up peanut butter in desserts, check out my guide to decadent dessert recipes!
Baking and Cooling the Monster Cookie Fudgy Brownies
Spread that thick batter evenly into your prepared pan—try to keep it level so you get even baking. Pop it into that preheated oven for about 30 to 35 minutes. You are aiming for perfection here, so test it right around the 30-minute mark. Stick a toothpick right near the center; you want it to come out with moist, fudgy crumbs attached—not wet, goopy batter. If it’s totally clean, you’ve baked too long and we’ll lose some of that signature fudge factor!
Once they pass the crumb test, pull the pan out. Now, here’s the hardest part of this whole process: you must let them cool completely in the pan on a wire rack. I usually let them sit for at least two hours, sometimes more. If you try to cut them warm, they will fall apart into a delicious mess, but you won’t get nice squares! When they are totally cool, grab those parchment overhangs and lift the whole slab out. Slice them up, and you’re ready to go!
Tips for Achieving Ultimate Monster Cookie Fudgy Brownies Texture
Getting the texture right in these **Monster Cookie Fudgy Brownies** is what separates a good bar from a life-changing one. It’s a balancing act between gooey center and chewy sides. My biggest secret, which I mentioned when we talked about baking time, is resisting the urge to bake them until they are totally dry. Seriously, don’t do it!
If you want that melt-in-your-mouth fudge factor, pull them out when those toothpick crumbs are still damp. They will continue to set up beautifully as they cool on the rack. That cooling period is just as critical as the baking time, so don’t rush it! If you’re looking for other cookie creations where texture is king, you should check out my ideas for a huge cookie cake.
For the edges, make sure you didn’t overmix the batter once the flour went in. Minimal mixing equals maximum tenderness throughout the bar. Plus, that little bit of peanut butter and the oats just naturally absorb moisture and help create that wonderful, slightly crisp-but-chewy perimeter we all fight over!
Ingredient Substitutions for Monster Cookie Fudgy Brownies
I know life happens in the pantry, and sometimes you reach for something and realize you’re short on a key ingredient. Don’t panic! While these **Monster Cookie Fudgy Brownies** shine with creamy peanut butter, you absolutely have wiggle room. If you only have crunchy peanut butter on hand, go for it! Just know that you might lose a tiny bit of that smooth swirl in the center, but you’ll gain some fantastic texture surprises instead. Check out how you can play with peanut butter in other ways here!
When it comes to the candies, if you can’t find M&M’s, maybe use peanut butter chips mixed with some chopped nuts, or even chopped-up wafer cookies if you have them lying around. Just make sure whatever you fold in doesn’t add too much extra liquid, or your fudgy layers will turn cakey on you. If you swap the semi-sweet chips for milk chocolate chips, expect a sweeter bar overall—it’s a trade-off, but a delicious one!
Serving Suggestions for Your Monster Cookie Fudgy Brownies
Look, these bars are already loaded wagons of flavor, so they don’t *need* much help. But if you’re serving them up for guests or just treating yourself to an epic dessert experience, I have a few favorite pairings. Since these are so intensely rich—all that chocolate, peanut butter, and sugar—you want something cool and creamy to cut through it.
My number one go-to is a giant scoop of vanilla bean ice cream. Yes, it’s a classic for a reason! The melting ice cream creates this amazing, creamy river around the warm brownie edges. Even better? If you want something homemade that tastes like a dream, try whipping up a batch of homemade Frosty-style dessert to eat alongside them. If you’re feeling less formal, a cold glass of milk is mandatory. Seriously, don’t even try to tell me otherwise!
Storing and Reheating Monster Cookie Fudgy Brownies
These are so rich that they actually taste even better the next day once everything settles together. You want to keep them in an airtight container, and if you’re planning on eating them within three days, the counter is totally fine! Don’t even bother with the fridge unless your kitchen is super hot. They’ll stay perfectly tender for up to four days this way.
If, by some miracle, you have any left after that, then yes, you can definitely freeze them! Wrap individual squares tightly in plastic wrap first. If you happen to want one slightly warmed up later, just zap a square in the microwave for about 10 to 15 seconds. It brings back that fresh-from-the-oven meltiness without drying out the bar at all.
Frequently Asked Questions About Monster Cookie Fudgy Brownies
I always get tons of questions once I post these, because everybody wants to know the secret to getting that perfect chewiness and fudge factor. Here are the things I hear most often when people ask about nailing these **Monster Cookie Fudgy Brownies**!
Can I use crunchy peanut butter for these brownies?
You totally can! If you’re out of creamy, or you just prefer that extra crunch, feel free to substitute it cup-for-cup. The main difference is that creamy peanut butter melts right into the batter, giving you those gorgeous, smooth ribbons of peanut butter goodness throughout your fudgy base. Crunchy peanut butter will disperse more like little islands in the brownie. It still tastes amazing, but the texture changes a tiny bit. It’s a personal preference, really!
What’s the trick to making sure they don’t dry out?
This is the number one concern with any brownie recipe, right? The secret is twofold: first, use packed brown sugar instead of relying only on white sugar. That molasses in the brown sugar is a moisture magnet! Second, and this is crucial, you *must* watch your baking time. Pull them out when the toothpick has moist crumbs attached, not when it’s clean. If you wait until it’s perfectly dry, they’ll be cakey by the time they cool down. Seriously, underbake them by about two minutes!
Can these Monster Cookie Fudgy Brownies be made ahead of time?
Yes, and I actually encourage it! Like many great bar cookies, these genuinely taste better the next day. I usually bake them on a Saturday afternoon, let them cool completely, cover the pan tightly, and then slice them on Sunday. The rest time lets all those flavors—the chocolate, the oats, the peanut butter—really meld together into one perfect bite. If you’re freezing them, make sure you slice them into squares *before* freezing, just like I noted in the storage section. If you need ideas for other recipes that taste great made ahead, check out this fun no-bake eclair cake!
Print
Monster Cookie Fudgy Brownies
- Total Time: 50 min
- Yield: 24 squares 1x
- Diet: Vegetarian
Description
Fudgy brownies loaded with classic monster cookie ingredients like peanut butter, oats, chocolate chips, and M&Ms.
Ingredients
- 1 cup unsalted butter, melted
- 1 1/2 cups granulated sugar
- 1 cup packed brown sugar
- 4 large eggs
- 1 teaspoon vanilla extract
- 3/4 cup unsweetened cocoa powder
- 1 cup all-purpose flour
- 1/2 teaspoon salt
- 1/2 cup creamy peanut butter
- 1 cup rolled oats
- 1 cup semi-sweet chocolate chips
- 1 cup M&M’s candies
Instructions
- Preheat your oven to 350 degrees F (175 degrees C). Line a 9×13 inch baking pan with parchment paper, leaving an overhang on the sides for easy removal.
- In a large bowl, whisk together the melted butter, granulated sugar, and brown sugar until smooth.
- Beat in the eggs one at a time, then stir in the vanilla extract.
- Whisk in the cocoa powder and flour until just combined. Do not overmix.
- Stir in the salt, peanut butter, rolled oats, and chocolate chips.
- Gently fold in the M&M’s candies.
- Spread the batter evenly into the prepared baking pan.
- Bake for 30 to 35 minutes, or until a toothpick inserted near the center comes out with moist crumbs attached, not wet batter.
- Let the brownies cool completely in the pan on a wire rack before lifting them out using the parchment overhang.
- Cut into squares and serve.
Notes
- For extra fudgy results, slightly underbake them by a few minutes.
- You can substitute peanut butter chips for some of the chocolate chips if you prefer.
- Prep Time: 15 min
- Cook Time: 35 min
- Category: Dessert
- Method: Baking
- Cuisine: American
Nutrition
- Serving Size: 1 square
- Calories: 250
- Sugar: 25
- Sodium: 80
- Fat: 14
- Saturated Fat: 7
- Unsaturated Fat: 7
- Trans Fat: 0
- Carbohydrates: 30
- Fiber: 1
- Protein: 4
- Cholesterol: 50
Keywords: monster cookie brownies, fudgy brownies, peanut butter, chocolate chip, M&M, oatmeal cookie bar