Easy Reese's Pieces Brookies (Cookie Mix Brownies)

These easy Reese's Pieces brookies combine a chewy cookie mix base with rich, fudgy brownies. Two convenient mixes, one irresistible dessert!

If you love chocolate and peanut butter together, you're going to love the idea behind these easy Reese's Pieces Cookie Mix Brownies! We're taking a simple bag of cookie mix and a boxed brownie mix and bringing them together in one delicious dessert.

The best part? You don't have to make either layer from scratch. This is shortcut baking at its finest!

Chocolate and Peanut Butter: A Match Made in Heaven

I grew up in the era of those unforgettable Reese's Peanut Butter Cup commercials. Remember the ones where two people would accidentally collide, getting peanut butter in someone's chocolate and chocolate in someone else's peanut butter?

There would be a little protesting at first, followed by the wonderful discovery that these two flavors were absolutely meant to be together.

Those commercials were all the rage when I was growing up, and I still remember them fondly.

Of course, Reese's Peanut Butter Cups had been around for decades before those advertisements came along, but the commercials certainly helped cement that delicious flavor combination in our minds.

I've always loved chocolate and peanut butter together. And if you've spent much time here at Out of the Box Baking, you've probably figured that out already!

Over the years, I've combined these two flavors in more recipes than I can count. Cookies, brownies, candies, and all sorts of other sweet treats have come out of my kitchen featuring that wonderful combination.

There's just something about rich chocolate paired with sweet, slightly salty peanut butter that keeps me coming back for more.

And today's recipe is another fun way to celebrate those flavors!

Can You Turn a Bag of Cookie Mix Into Brookies?

Absolutely! And that's exactly what we're doing today.

If you've ever wondered how to doctor a bag of cookie mix and turn it into something beyond ordinary cookies, this is a great place to start.

We're using a prepared Reese's Pieces cookie dough as the bottom layer and topping it with rich chocolate brownie batter.

The cookie dough gets a short head start in the oven before the brownie batter goes on top. This helps the bottom layer begin setting before we add all that chocolate goodness.

The result is a layered dessert that's part cookie, part brownie, and completely inspired by that classic chocolate-and-peanut-butter combination.

And because both layers start with convenient store-bought mixes, the preparation couldn't be much simpler.

Ingredients for Reese's Pieces Cookie Mix Brownies

You'll find a full printable recipe card at the bottom of this post, but here's a quick look at what you'll need.

• 1 bag Reese's Pieces cookie mix, plus the ingredients called for on the package
• 1 box chocolate brownie mix, plus the ingredients called for on the package
• Nonstick baking spray or parchment paper for preparing the pan

That's it!

The cookie mix already contains those colorful little Reese's Pieces candies, so there's no need to purchase additional candy for this recipe.

I used a 9×13-inch baking pan, which gives both layers room to bake without becoming excessively thick.

How to Make Reese's Pieces Cookie Mix Brownies

These brownies come together in just a few simple steps.

Step 1: Prepare the oven and pan

Preheat your oven to 350°F. Prepare a 9×13-inch baking pan with nonstick baking spray or parchment paper.

Step 2: Mix the cookie dough

Prepare the bagged Reese's Pieces cookie mix according to the package directions. Once the dough is ready, press it evenly into the bottom of your prepared baking pan. Try to spread it all the way to the corners so the cookie layer is relatively even.

Step 3: Prebake the cookie layer

Place the pan in the preheated oven and bake for 8 minutes. The cookie dough won't be completely baked at this point, and that's fine. We're simply giving it a head start before adding the brownie batter.

Step 4: Prepare the brownie batter

While the cookie layer is prebaking, prepare your boxed brownie mix according to the package directions. Stir until the ingredients are combined.

Step 5: Add the brownie layer

Remove the partially baked cookie layer from the oven. Carefully pour the prepared brownie batter over the cookie dough, spreading it gently toward the edges of the pan. If a little cookie dough rises into the brownie batter, don't worry. You can gently swirl it into the chocolate layer for a slightly marbled appearance. If you're adding a few Reese's pieces candies to the top, this is the time to do it.

Step 6: Finish baking

Return the pan to the oven and bake for approximately 32 additional minutes, or until the brownie layer is set. The top should develop that beautiful crackly brownie appearance, and a toothpick inserted into the center should come out with moist crumbs rather than liquid batter.

Keep in mind that baking times may vary depending on your oven and the specific mixes you're using.

Total baking time: approximately 40 minutes, including the initial 8-minute cookie prebake.

Step 7: Cool before slicing

Remove the pan from the oven and place it on a wire rack. Allow the brownies to cool thoroughly before cutting them into squares. This gives both layers time to firm up and makes slicing much easier.

Why Prebake the Cookie Dough?

You might be wondering why we don't simply put both layers into the pan at the same time. It's a good question!

Cookie dough and brownie batter have different textures, moisture levels, and baking requirements. By prebaking the cookie dough for a few minutes, we give it a chance to begin setting before pouring the much softer brownie batter over the top. This can help prevent the cookie layer from remaining overly soft beneath the brownies. The goal is to have two distinct but delicious layers that bake together into one dessert.

What Do These Reese's Pieces Brookies Taste Like?

Oh, my goodness, friends. These turned out unbelievably tasty!

The rich, fudgy brownie layer pairs beautifully with the Reese's Pieces cookie base, giving you two delicious textures in every bite. The cookie layer adds that wonderful peanut butter flavor, while the brownie layer brings all the chocolate goodness.

And those little Reese's Pieces candies make the combination even more fun!

In fact, I knew almost immediately that I needed to package these up and give them away once they cooled. Some desserts are simply too tempting to leave sitting on the kitchen counter, and these definitely fall into that category!

If you're a fan of chocolate and peanut butter, I think you're going to love this easy shortcut recipe.

Variations on This Easy Cookie Mix Brownie Recipe

One of my favorite things about shortcut baking is discovering how many different desserts can come from a couple of ordinary mixes.

Once you've mastered this basic method, you can experiment with other cookie flavors.

Chocolate Chip Cookie Mix Brownies: Use a bag of chocolate chip cookie mix for a classic chocolate chip cookie and brownie combination.

Peanut Butter Cookie Mix Brownies: Try a peanut butter cookie mix underneath your favorite chocolate brownie batter.

Sugar Cookie Mix Brownies: A simple sugar cookie layer could provide a buttery contrast to rich chocolate brownies.

Double Chocolate Cookie Mix Brownies: For serious chocolate lovers, combine chocolate cookie dough with chocolate brownie batter.

These are ideas for future variations, so keep in mind that different cookie mixes may need adjustments to baking time.

More Chocolate and Peanut Butter Treats You'll Love

If you're anything like me, you can never have too many chocolate-and-peanut-butter desserts in your recipe collection.

Here at Out of the Box Baking, I've shared plenty of recipes inspired by this wonderful flavor combination, including peanut butter cookies, homemade candies, and other chocolate treats.

And if you enjoy the idea of combining cookie dough and brownies, don't miss my Snickers Cookie Dough Brownies. They're another fun way to turn convenient store-bought ingredients into a special dessert.

You might also enjoy my How to Doctor a Brownie Mix tutorial, where I share more ideas for transforming an ordinary box of brownie mix.

Frequently Asked Questions

Can I use a different brand of cookie mix?

Yes! You can experiment with other bagged cookie mixes, although the amount of dough and baking time may vary.

Can I use a different brownie mix?

Absolutely. Choose a brownie mix you enjoy and prepare it according to the package directions. Be aware that different package sizes and formulations may affect baking time.

Do I have to prebake the cookie layer?

I recommend it. The short prebake gives the cookie dough a head start and helps the two layers bake more evenly.

How do I know when the brownies are done?

Look for a set, crackly brownie top and edges that appear baked. A toothpick inserted into the center should show moist crumbs, not liquid batter.

Can I add more Reese's Pieces?

Certainly! You could sprinkle additional candies over the top before baking or add some after baking for extra color and crunch.

How should I store these brownies?

Once completely cooled, keep them in an airtight container at room temperature for approximately 3–4 days, provided the mixes and added ingredients don't require refrigeration. For longer storage, freeze individual portions in a freezer-safe container.

Final Thoughts

I've always believed that you don't have to make everything from scratch to create something special in the kitchen.

Sometimes the most fun recipes begin with ordinary ingredients and a little imagination.

These Reese's Pieces Cookie Mix Brownies are a perfect example of that philosophy. We're taking two convenient baking mixes and combining them into a dessert inspired by one of my all-time favorite flavor pairings: Chocolate and peanut butter. Some combinations just never get old!

Thanks for stopping by Out of the Box Baking. I hope this recipe inspires you to look at that next bag of cookie mix and imagine all the delicious possibilities.

See you next time, friends! (And don't forget to pin some photos to your Pinterest boards before you go!)

Janice Thompson is a professional baker, cake designer, and author with over 20 years of experience creating unique cakes and desserts. She’s the creator of Out of the Box Baking, where she shares her favorite doctored cake mix recipes, tutorials, and baking tips. Learn more →