Brownie Cookie Cake with Peanut Butter Buttercream

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Whenever a family birthday rolls around, I love creating a beautiful cake with all of their favorite flavors to celebrate. My husband, Joel turned 33 in February, and of course, I had to create a cake including all of his favorite things, peanut butter, chocolate chip and brownies. His Brownie Cookie Cake with Peanut Butter Buttercream turned out AMAZING.

Brownie Cookie Cake with Peanut Butter Buttercream

Before I became a full-time food blogger, I had a cupcake business, Sweet Little Things & Co and made the most delicious cupcakes/frosting. I had to leave that business in the dust because eating spoonfuls of frosting on a daily basis was not helping with my figure. I tried to contain myself from tasting and sampling, but I couldn’t because my buttercream frosting is that BOMB.

Peanut Butter Buttercream

How to make perfect Buttercream Frosting?

  • Use both, vegetable shortening and butter.
  • Powdered Sugar
  • Milk or heavy cream
  • Vanilla Extract

First, it is super important for the butter to me at room temperature, but not too warm. Soft to the touch but not melting is key. Next, using milk or cream thins out the buttercream and gives it a smoother texture that makes it more enjoyable to eat. Finally, it is super important to measure the powdered sugar correctly. To do that simply spoon the powdered sugar from the package to your dry measuring cup. Use a straight edge, like a dinner knife, to level off the top of the sugar so it’s even with the top of the cup.

Brownie Cookie Cake layered on cake stand
Brownie Cookie Cake with Peanut Butter Buttercream

What is needed for this Brownie Cookie Cake?

  • Cookie Dough
  • Boxed Brownie mix
  • Milk Chocolate
  • Butter
  • Vegetable Shortening
  • Milk
  • Vanilla Extract
  • Powdered Sugar
  • Chocolate Chip Cookies

If you are looking for the perfect birthday cake or just a fun dessert, be sure to give this recipe a try. Also, if you love this cake, be sure to rate and review in the comment section at the bottom of the post.

Brownie Cookie Cake with Peanut Butter Buttercream

Brownie Cookie Cake with Peanut Butter Buttercream I

By: Ashley McCrary
The most delicious cake that you will ever have in your life. This decadent Brownie Cookie Cake is layered with a cookie cake followed by a brownie cake along with ganache and topped with peanut butter buttercream frosting. 
Prep Time: 25 minutes
Cook Time: 35 minutes
Servings: 18 servings


Cakes (makes 4 9-inch cakes)

  • 2 16.5 oz Pillsbury refrigerated chocolate chip cookie rolls
  • 2 boxes brownie mix

Chocolate Ganache

  • 8 ounces semi-sweet chocolate chips
  • 1 cup 8 ounces heavy whipping cream

Peanut Butter Buttercream Frosting

  • 2 cups unsalted butter
  • 1/2 cup all vegetable shortening I use Spectrum
  • 6 1/2 cups powdered sugar
  • 1 1/2 tsp pure vanilla extract
  • 2 tbsp milk or heavy cream
  • 1/2 cup creamy peanut butter
  • Pinch of salt


Brownie and Cookie Cakes

  • Preheat oven to 375F
  • Grease (4) 9-inch cake pans. Set to the side.
  • Make the brownie batter by following the instructions and ingredients on the box. Be sure to make 2 boxes.
  • Pour the brownie batter into 2 of the greased cake pans. 
  • Remove the packages of the cookie dough and place in the greased cake pans. One package for each pan.
  • Press the cookie dough evenly into the pan.
  • Place all 4 cake pans into the oven for 2-25 minutes. (I usually add the brownie pans to the top rack and cookie pans on the bottom rack.)
  • Remove from the oven and place on a wire rack to cool completely.

Chocolate Ganache

  • Pour the heavy whipping cream into a medium microwave safe bowl and heat in the microwave for 1 minute. Make sure to keep an eye on it so it doesn't bubble over.
  • Transfer the chocolate chips to a large mixing bowl and pour the warm heavy whipping cream over the chocolate and let it sit for 2-3 minutes. Start whisking slowly in the middle of the bowl, and continue whisking in one direction until the mixture is smooth and well combined.
  • Allow to cool for about 10 minutes.


  • In a stand mixer, add the butter and the vegetable shortening. Beat together on medium speed until combined and fluffy.
  • Slowly add the vanilla extract, milk along with the powdered sugar.
  • Add the peanut butter and beat together for 40 seconds or until fluffy and stiff.


  • Place one cake layer on a cake stand. Carefully spread an even layer of peanut butter buttercream over the top followed by chocolate ganache. 
  • Repeat this process for each all 3 layers.
  • Decorate the outside of the cake as desired. I used a 2110 tip and just did quick half circles around the entire cake.
  • Top the cake with crushed chocolate chip cookies and drizzle with more ganache if desired. 


  • This cake is amazing eating right away. However, if you do refrigerate, the brownie and cookie will harden. To make this amazing and soft after being refrigerated, I will microwave each slice for 15 seconds. 
  • I think my family enjoyed it more warm than cold. 
  • For the brownie mix I used Duncan Hines

Nutrition information is automatically calculated, so should only be used as an approximation.

Tried this recipe?Mention @healthylittlepeach or tag #healthylittlepeach!

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Brownie Cookie Cake with Peanut Butter Buttercream

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About Me

Mother, wife, cookbook author, recipe creator an open book

Welcome to Healthy Little Peach. I’m Mac, the lady behind the recipes. I believe in living a healthy lifestyle that consists of a mix of healthy whole foods, and full-fat comfort meals. Life is too short not to enjoy good food while maintaining a healthy body and mind. Here you will find gluten-free, dairy-free, paleo, keto, and even full-fat comfort recipes. Let’s have fun in the kitchen together!

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  1. You mention milk in the buttercream instructions but there is no milk listed. How much do you add?