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Combining a delicious peanut butter blondie with decadent chocolate fudge frosting is the stuff dreams are made of. This Peanut Butter Cookie Cake actually happened by accident. I was making my Peanut Butter Blondies for some special guests, but I decided I wanted them to be thicker. When I was playing around with the recipe, the center sort of sunk as it cooled. I was disappointed because I wanted even blondies in the pan. But then I thought, hmmmmm. I could slab on some frosting in the middle and it would very likely be delish! And if I were adding frosting, it is more like a cake, and if I’m making a cake, it should be a festive round. Then I was concerned about being able to remove it from a square or round baking pan. So, I grabbed my springform pan to ensure there would be no cake removal issues. And thus, this Peanut Butter Cookie Cake was born!

overhead view of peanut butter cookie cake with a plated slice on its side
The best of peanut butter blondies and chocolate fudge frosting make this cookie cake super outstanding!

When thinking about the ideal chocolate frosting for this cookie-cake, I wanted a deep chocolate, fudgy frosting and immediately thought of the chocolate frosting from King Arthur Baking Company’s classic yellow cake recipe. I love that frosting. I barely adapted it to top this cookie-cake.

How to Make a Peanut Butter Cookie Cake

Honestly, this is such an easy thing to make, and the result is sort of show-stopping and downright delicious. Any peanut butter lover will be satisfied!

1. Melt the butter

Over the lowest heat, melt the butter in a small pot. Stir it occasionally to make it go slightly faster. It should only take a couple minutes. You can absolutely grab butter from the freezer and melt it down. No need to let the butter get to room temperature for this recipe.

2. Stir in the Sugars

There is no need to wait for the butter to cool before mixing in the sugars. Adding the sugars into the warm butter will dissolve most of the sugar, which is what will help create a flaky, crinkly top.

3. Stir in Beaten Eggs

It’s best to use cold eggs here, again because that helps get a crinkly top. You can certainly use room temperature eggs if you already removed them from the refrigerator. It is much easier to incorporate the eggs if they are already beaten, rather than cracking each egg into the batter.

4.  Mix in the Peanut Butter

Make sure to mix in the peanut butter really well. I highly recommend using only traditional, smooth peanut butter (not natural), either Skippy or Jif. (I’m partial to Skippy.) Do not use a generic brand, as they tend to have more sugar and a poor consistency for baking. You could certainly use a crunchy version if you like that. We add a little vanilla too for deeper flavor.

5. Stir in Flour and Mix-ins

Fold in the dry ingredients, just to the point where they are no longer visible. Do not overmix, as you do not want to develop the gluten. Then fold in whatever mix-ins you decide on.

6. Bake and Cool

Spread the batter evenly into a prepared springform pan. A parchment round is very good to use on the bottom of the pan. Bake for 53-57 minutes, until a toothpick inserted in the middle comes out clean. Allow the cookie cake to cool completely before removing it from the pan. As it cools, the middle will sink a bit. Don’t panic — that’s a good thing! Once cooled, remove the cookie cake from the pan and place on a serving platter.

7. Frost the Peanut Butter Cookie Cake

The frosting comes together super fast and easily. Make sure to make it in the order described in the recipe. To keep the frosting just over the sunken middle, put the frosting in a piping bag and pipe a rope of frosting around the outside permitter of where you want it. Then fill in the circle with the rest of the frosting and decorate as desired.

overhead view of peanut butter cookie cake
With minimal piping, this cookie cake can be as pretty as it is delicious!

Frequently Asked Questions to Make a Peanut Butter Cookie Cake

Do I have to use a springform pan?

You could probably use a 9″ round cake pan if you use parchment on the bottom of the pan with enough extra coming up the sides so that you can pull the cookie cake out of the pan once cooled. You want to avoid turning the cookie cake over when removing from the pan.

Does the butter need to be at room temperature?

No. Grab butter from the freezer or refrigerator. You need to melt the butter, so no need to bring it to room temperature.

Do I need to mix together the dry ingredients before adding it to the wet ingredients?

Generally, it is best to whisk together the dry ingredients before mixing them with the wet ingredients, but for treats like brownies and blondies, I usually don’t find it necessary, which is great because it’s one less bowl to clean!

Peanut Butter Cookie Cake

5 from 5 votes
Prep Time 10 minutes
Cook Time 55 minutes
Total Time 1 hour 5 minutes
Servings 18 slices
Calories 439
The best peanut butter blondie, baked to be cut like cake, and topped with decadent chocolate fudge frosting.

Ingredients

Peanut Butter Cookie Cake:

  • 113 grams unsalted butter (8 Tablespoons or ½ cup)
  • 220 grams light brown sugar (1 cup)
  • 150 grams sugar (¾ cup)
  • 3 eggs, refrigerator cold, beaten
  • 192 grams peanut butter (¾ cup)
  • 2 teaspoons vanilla
  • 210 grams all purpose flour (1¾ cup)
  • ¼ teaspoons baking soda
  • ¼ teaspoons baking powder
  • ¾ teaspoons salt
  • 339 grams Reese’s Pieces, Peanut Butter M&Ms, chocolate chips, peanut butter chips, or any combination of them (1½ cups)

Chocolate Fudge Frosting:

  • 53 grams Dutch process cocoa (½ cup plus 2 Tablespoons)
  • 227 grams confectioner’s sugar (2 cups)
  • teaspoon salt
  • 37 grams hot milk
  • teaspoons vanilla extract
  • 113 grams unsalted butter, at room temperature (8 Tablespoons or ½ cup)

Instructions 

  • Preheat oven to 350° F. Line an 9 inch springform baking pan with parchment paper.
  • In a 2-3 quart saucepan, melt the butter over low heat. Remove from heat and allow to cool to room temperature.
  • Mix in sugar and brown sugar. Stir in beaten eggs.
  • Mix in peanut butter and vanilla.
  • Mix in flour, baking soda and baking powder, just until fully incorporated and no flour is visible.
  • Stir in any mix-ins just until incorporated. Spread batter into prepared pan.
  • Bake for 50-55 minutes. The cookie cake is done when the edges are browned and a toothpick inserted in the middle comes out clean. Allow the cookie cake to cool completely in the pan. The middle will sink as it cools.
  • Frosting. In a bowl of an electric mixer (or bowl with a hand mixer), mix the cocoa powder, half the confectioner’s sugar and salt. Stir in the hot milk and the vanilla. Add the butter and rest of the confectioner’s sugar, beating until light and fluffy, approximately 2-3 minutes.
  • Assembly. Slide a metal spatula around the inside edge of the baking pan to loosen the blondie cake from the sides. Release the side portion of the springform pan. Using a spatula, lift the cookie cake onto a serving plate. Spread the frosting over the sunken part of the cookie cake.

Notes

  • You can use frozen, cold, or room temperature butter since you are melting it under the lowest heat possilbe anyway.
  • For a flaky top, mix in the sugars immediately after removing the butter from the heat, once it is melted. The heat from the butter will dissolve most of the sugar, which will help create a flaky top.
  • Make sure to allow the cookie cake to cool completely before removing it from the pan and frosting it.
Author: Rob Finkelstein
Calories: 439kcal
Course: Dessert, Snack
Cuisine: American
Keyword: Blondies, frosting, M&Ms, peanut butter, reese's pieces

Nutrition

Calories: 439kcal | Carbohydrates: 59g | Protein: 6g | Fat: 21g | Saturated Fat: 11g | Polyunsaturated Fat: 2g | Monounsaturated Fat: 6g | Trans Fat: 1g | Cholesterol: 57mg | Sodium: 198mg | Potassium: 161mg | Fiber: 2g | Sugar: 46g | Vitamin A: 399IU | Vitamin C: 1mg | Calcium: 56mg | Iron: 2mg

4 Comments

  1. 5 stars
    Everything about this, from the cookie cake to the chocolate frosting, is just SO good! My family and I love it! Thanks for the recipe

  2. 5 stars
    you come up with another genius baked treat despite not being able to achieve first your blondies, the addition of chocolate on top is such a double treat. I’m a big fan of PB’s will surely make this.

  3. 5 stars
    What a fabulous idea! This was a huge hit when I made this for my family. I’m already planning on making it again soon, it was so good!

  4. Amanda Dixon Reply

    5 stars
    This was such a fun and delicious cake! I just love peanut butter and blondies, so this was my perfect dessert — highly recommend making!

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