She combined peanut butter and browned butter. This cake is delicious, but this frosting is divine. Make this. Or make any cake you please, and top it with this frosting. (I couldn't make the peanut butter cheesecake I wanted for my birthday as it wouldn't hold up without a refrigerator for our trip to our land, so I made a simple chocolate cake and topped it with this.)
Browned Butter Peanut Butter Snack Cake
Cake
1/2 cup butter, to be browned
1/8 cup canola oil
1/3 cup peanut butter
1/3 cup sugar
2 tsp. vanilla
1/2 tsp. baking powder
1/4 tsp. salt
1/4 tsp. (heaped) baking soda
2 eggs, room temperature
1 cup cake flour
1/2 cup buttermilk
1 Tbsp. cocoa
1/2 Tbsp. milk
Frosting
1/2 cup butter, browned
1/4 cup butter, softened
1/3 cup peanut butter
1 tsp. vanilla
1/2 tsp. sea salt
2 1/4 cups powdered sugar
2 Tbsp. heavy cream (or milk)
Preheat oven to 350°F. Grease and line an 8 x 8 pan with parchment paper. Over medium heat, melt the butter. Cook until butter is browned and nutty. (You can brown the butter needed for the frosting at the same time, and set half aside. Just make sure to get the browned bits in both the cake and frosting portions as those contain the most flavor.)
Pour browned butter into a bowl. Add peanut butter, vanilla, sugar and oil. Whisk together until smooth. Whisk in the eggs. Gently stir in the dry ingredients. Add the buttermilk, and stir until smooth. Pour half the batter into the pan. Add the cocoa powder and milk to the remaining half of the batter, and stir until smooth. Dollop the chocolate batter throughout the pan, and gently swirl with a knife. Bake 20 to 30 minutes or until cake is done.
To make the frosting, chill the browned butter until it's solid but not fully hardened. Using a mixer, beat together the butters until fluffy. Add in peanut butter, vanilla and salt, and beat to combine. Gradually add the powdered sugar, and mix until incorporated. Drizzle in the cream or milk, and beat on high until fluffy. (You can add more milk if needed to achieve the desired texture.)
Spread frosting on cooled cake. Enjoy. Makes an 8 x 8 cake.