Peanut butter cake plus peanut butter buttercream? This sheet cake recipe is over the top delicious! Super great for celebrations like Vintage Kitty's four year anniversary, but it's great for birthday parties and potlucks too!
Measure out all ingredients and let them come to room temperature before beginning. Combine the flour, baking powder, baking soda and salt in one bowl. Combine the buttermilk and vanilla in another.
Preheat oven to 350F then grease and flour a 9 by 13 inch cake pan.
Whip butter with brown sugar until light and fluffy then add peanut butter and mix to combine.
Add in the eggs one at a time, beating each just to combine.
With mixer running, pour in oil in a slow steady stream.
Add dry ingredients alternating with buttermilk mixture in three intervals, beginning and ending with the flour. With the last addition of flour, be careful to not overmix. A little unmixed flour is okay!
Spread batter into prepared cake pan and transfer to preheated oven. Bake 40-45 minutes or until a toothpick comes out clean.
Let cake cool at least 15 minutes before turning out cake (if desired). Let cake cool completely before frosting.
Peanut Butter Buttercream
Cream butter with peanut butter then add in vanilla extract.
Slowly add in sifted powdered sugar, whipping between each addition.
Add in heavy cream, 2 tablespoons at a time, mixing thouroughly each time.
Once all the heavy cream has been added, whip buttercream until light and fluffy.
With an offset spatula, frost cake and sprinkle with chopped nuts and grated white chocolate if desired.
I found the Kitchen Aid whisk attachment was preferable to the paddle for this recipe.
Peanut butter is sticky and heavy. Make sure to scrape the bottom of your bowl with a spatula between additions.