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Old Fashioned Peanut Butter Cake

A food old fashioned peanut butter sheet cake with a crazy amazing peanutty frosting!

Course Dessert
Cuisine American
Keyword Cake Recipe, Homemade Cake Recipe, Homemade Peanut Butter Dessert, Old Fashioned Peanut Butter Cake, Peanut Butter Cake
Author Sunup to Sundown

Ingredients

  • 2 cups all purpose flour
  • 2 cups granulated sugar
  • 1 tsp baking soda
  • 1 tsp salt
  • 1/2 cup unsalted butter 1 stick
  • 1 cup water
  • 1/2 cup creamy peanut butter Use regular peanut butter, 'natural' peanut butter does not work as well in this recipe.
  • 1/2 cup oil
  • 2 large eggs
  • 1/2 cup buttermilk
  • 1 tsp vanilla extract

Frosting

  • 1/2 cup unsalted butter 1 stick
  • 1/2 cup creamy peanut butter
  • 6 tbsp buttermilk
  • 1 tsp vanilla extract
  • 3 cups powdered sugar

Instructions

  1. Preheat your oven to 350 degrees F.

  2. Spray or prepare a 9 x 13 pan.

  3. Whisk together the flour, sugar, baking soda, and salt. Set aside.

  4. Heat the butter and water in a medium/large saucepan until it comes to a boil. Take off the heat and whisk in the peanut butter and oil until smooth. Let cool for a few minutes then whisk in the eggs, buttermilk, and vanilla until well blended.

  5. Add the dry ingredients to the wet ingredients and whisk just until combined.

  6. Pour the batter into the prepared pan and bake for 40-45 minutes, until the top is golden, and a toothpick inserted in the center comes out clean. Set the cake on a cooling rack while you make the frosting.

  7. To make the frosting, put the butter, peanut butter, and buttermilk in a saucepan and bring to a full boil. Take off the heat and beat in the vanilla and powdered sugar, adding a cup at a time, until the frosting is smooth. You can keep the frosting on gentle heat, stirring constantly, if needed to get it completely smooth before pouring over the cake. Note: if your frosting is very stiff and not pourable, add a little bit more buttermilk to think it out.

  8. Pour the hot frosting over the warm cake, working quickly because the frosting sets up immediately. Spread evenly over the cake.

  9. If desired, garnish with roasted peanuts.

Recipe Notes

If you want to use chunky peanut butter for this cake recipe, then do it.  We would still recommend using smooth peanut butter for the frosting but, it's your kitchen and your rules. 

To make homemade buttermilk, simply add 1 teaspoon of vinegar or lemon juice to one cup of milk.  Let sit for a few minutes.