This peanut butter cookie cake is soft and chewy with a delicious peanut butter flavor. Filled with peanut butter candies and decorated with chocolate frosting – it’s perfect if you love peanut butter.
After making a chocolate chip cookie cake, a double chocolate cookie cake and a red velvet cookie cake – I realized I was due to make a peanut butter version. This peanut butter cookie cake is essentially a giant peanut butter cookie that’s extra thick and chewy. I mixed in chocolate chips and Reese’s Pieces, and piped the edges with creamy chocolate frosting. It’s the perfect birthday cake for anyone who loves peanut butter, and its way easier to make than a layer cake.
The Perfect Peanut Butter Cookie Cake
If you’ve every made peanut butter cookies before, this recipe will be very familiar. In this recipe that we’re using real butter for the most flavor, plus a combination of brown sugar and white sugar. Brown sugar adds more flavor and moisture, leading to a chewier cookie texture. Then there’s 1 egg plus 1 extra egg yolk. The extra egg yolk adds tenderness and is really key to the perfect cookie cake texture.
Pro Tip: It’s important to measure the flour very carefully or your cookie cake can get dry. This recipe calls for 1 ⅓ cups all-purpose flour. For the most accurate results, use a scale. 1 ⅓ cups flour weighs 166 grams. If you don’t have a scale, whisk the flour first. Then spoon into a dry measuring cup and level off the top.
It can be very tempting to add in extra chocolate chips or Reese’s. However, if you add too many I find it hard to slice the cookie cake. Therefore, I don’t recommend adding in more than 1 cup in total of mix-ins.
You can bake your cookie cake in either a 9-inch springform pan or in a 9-inch pie plate. I chose the springform pan, because you can then unclamp the outer ring, lift it off the base, and place on your preferred serving plate. If you plan to bake it in a pie plate, then I find it best to serve directly from the pie plate.
The chocolate frosting recipe included will be enough to pipe around the edges of the cake, plus potentially a little extra. If you’d prefer a double dose of peanut butter, you could use this peanut butter frosting recipe and divide it in half.
I love this peanut butter cookie cake because it has a delicious peanut butter flavor, a chewy texture and is perfect for anyone who reaches for the cookie jar before a slice of layer cake. Soft, easy and filled with Reese’s Pieces – there’s a lot to love about this massive cookie!
And if you need some more peanut butter treats, then be sure to try:
Peanut Butter Cookie Cake
- 9-inch springform pan
Peanut Butter Cookie Cake
- ½ cup unsalted butter (112 grams) softened to room temperature
- ½ cup brown sugar (100 grams) light or dark
- ½ cup granulated sugar (100 grams)
- ¾ cup creamy peanut butter (180 grams) do not use natural or homemade
- 1 large egg
- 1 large egg yolk discard the white
- 1 teaspoon vanilla extract
- 1 ⅓ cups all-purpose flour (166 grams) measured properly
- ½ teaspoon baking powder
- ¼ teaspoon salt
- ½ cup chocolate chips
- ½ cup Reese's Pieces
- ½ cup unsalted butter (112 grams) softened
- 2 cups powdered sugar (220 grams)
- ¼ cup cocoa powder (20 grams)
- 1-2 tablespoons cream or milk - as needed
Peanut Butter Cookie Cake
- Preheat the oven to 350F (180C) degrees.
- Line the bottom of a 9-inch springform pan with parchment paper and lightly spray the sides with non-stick cooking spray. Alternatively, lightly spray a 9-inch pie plate with non-stick cooking spray.
- In a large bowl, beat together the butter, brown sugar and white sugar until fluffy.
- Mix in the peanut butter until smooth.
- Then mix in the egg, additional egg yolk and vanilla extract.
- With the mixer on a low speed, beat in the flour, baking powder and salt until combined.
- Stir in the chocolate chips and Reese's Pieces (or whatever mix-ins you're using).
- Spoon the cookie dough into the prepared pan and flatten down into an even layer.
- Bake in the preheated oven for about 24-28 minutes, or until the top is golden.
- Remove from the oven and cool fully if you're adding frosting on top.
- Beat the butter until smooth.
- Mix in 1 cup powdered sugar, starting with the mixer on a low speed.
- Mix in the cocoa powder.
- Mix in the rest of the powdered sugar about ½ cup at a time, alternating with a tablespoon of cream or milk until the desired sweetness and thickness is reached.
- If your cookie cake is in a springform pan, unclamp the outer ring of the pan. Carefully lift the cookie cake off the base of the springform and place on a serving plate or cake stand.
- Transfer the frosting to a piping bag (I used a 1M tip). Pipe around the edges of the cake. You may have some frosting leftover if you'd like to frost a message on the cake with a thinner piping tip.
- Pan Sizes: This recipe can be made in a 9-inch springform pan or a 9-inch pie plate. The bake time will be about the same. There is too much batter for an 8-inch springform - the top will get too browned before the cookie is properly baked.
- Peanut Butter: Make sure to use commercial peanut butter that does not separate. Homemade or natural peanut butter can separate and end up with inconsistent results due to the oil separating.
- Eggs: You'll need 2 eggs in total. You'll use 1 whole egg plus just the egg yolk of the second egg. Do not add 2 whole eggs to the cookie cake.
- Mix Ins: Use 1 cup in total of your preferred mix-ins. I used ½ cup chocolate chips and ½ cup Reese's Pieces. Feel free to use entirely chocolate chips, peanut butter chips, M&Ms or a combination.
- Storage: Store in an airtight container at room temperature for up to 4 days. The cookie will be the softest on the first day.
- Nutrition: Details are an estimate only and based on 1 slice with frosting, assuming the cake is sliced into 10 equal-sized pieces and all the frosting is used.