For the peanut butter cake:
2¼ cups flour
2 teaspoons baking powder
1 teaspoon baking soda
½ teaspoon salt
¾ cup creamy peanut butter
6 tablespoons unsalted butter, softened
½ cup sugar
½ cup packed brown sugar
1 cup plus 2 tablespoons buttermilk
For the Peanut Butter Cream Cheese Frosting:
8 ounces cream cheese, softened
½ cup unsalted butter, softened
⅓ cup plus 2 tablespoons creamy peanut butter, divided
Pinch of salt
2 cups powdered sugar, sifted
2 teaspoons vanilla
Make the cake:
Preheat oven to 350 degrees. Grease and flour two 8 or 9-inch round cake pans. Set aside.
In a medium bowl, whisk together flour, baking powder, soda and salt. Set aside.
In the bowl of an electric stand mixer fitted with a paddle attachment, cream together peanut butter, butter and sugars until fluffy, about 3 minutes.
Add eggs, one at a time, beating at medium speed for 1 minute between each addition. Stop mixer and scrape down the sides of the bowl as necessary.
With the mixer on low speed, add half of the flour mixture to the butter mixture. Slowly add all of the buttermilk. When the batter just starts to come together, add the remaining flour mixture, beating on low speed until the mixture just starts to come together. Remove the bowl from the mixer and finish incorporating the ingredients with a spatula. (This will prevent you from over-mixing, thus keeping your cake from getting tough!)
Divide batter between the prepared pans. If you’re an uber-nerd (like me) and have a kitchen scale, you can use it to make sure they are of even weights. Bake for 30-45 minutes, rotating pans as needed halfway through to ensure even baking, or until a cake tester inserted in the cake comes out clean.
Allow cakes to cool in the pans for 10 minutes before inverting onto wire racks. Cool completely before frosting.
Cake will last, wrapped, in the refrigerator for up to 4 days.
Make the frosting:
Place cream cheese in the bowl of a stand mixer fitted with a paddle attachment and beat for about 1 minute, ensuring that it is soft and pliable. Scrape down the sides of the bowl and add the butter. Beat the butter and cream cheese on medium speed for 1 minute until thoroughly combined.
add ⅓ cup of the peanut butter to the bowl. Beat for 30 seconds on medium speed until well combined. With the mixer on low, add the salt and powdered sugar, followed by the vanilla. Once everything is almost incorporated, turn the mixer to medium speed and beat until all of the powdered sugar has disappeared and mixture is velvety soft, scraping down the sides of the bowl as needed.
If using immediately, add in the last 2 tablespoons of peanut butter and fold in with a spatula, leaving streaks of peanut butter throughout. Use immediately to frost cakes or cupcakes.
If storing for later use, spoon into an airtight container, add peanut butter, swirl into the frosting and store in the fridge until ready to use. Bring to room temperature before frosting cakes or cupcakes.
Frosting will last, in an airtight container, in the refrigerator for up to 7 days.