Ingredients:

  • 2 cups (250g) all-purpose flour
  • 2 cups (400g) granulated sugar
  • 3/4 cup (65g) unsweetened cocoa powder
  • 2 tsp (10g) baking soda
  • 1 tsp (5g) baking powder
  • 1 tsp (6g) salt
  • 1 cup (240ml) buttermilk, room temperature
  • 1/2 cup (120ml) vegetable oil
  • 2 large eggs, room temperature
  • 2 tsp (10ml) vanilla extract
  • 1 cup (240ml) boiling water
  • 1 cup (225g) unsalted butter, softened
  • 1 cup (250g) creamy peanut butter
  • 4 cups (500g) powdered sugar
  • 3 tbsp (45ml) heavy cream
  • 1 tsp (5ml) vanilla extract
  • 1/4 tsp (1.5g) salt
  • 1 cup (150g) Reese's Peanut Butter Cups, chopped

Instructions:

  1. Preheat oven to 350°F (175°C). Grease two 9-inch cake pans and line the bottoms with parchment paper.
  2. In a large bowl, whisk together flour, sugar, cocoa powder, baking soda, baking powder, and salt until combined.
  3. Add buttermilk, vegetable oil, eggs, and vanilla extract. Beat on medium speed for approximately 2 minutes until the batter is smooth and glossy.
  4. Carefully stir in the boiling water by hand until combined; the batter will be thin.
  5. Divide the batter evenly between the two prepared cake pans and bake for 30 minutes or until a toothpick comes out clean.
  6. Allow cakes to cool completely before frosting.
  7. Prepare the frosting by beating softened butter and peanut butter together. Gradually incorporate powdered sugar, heavy cream, vanilla extract, and salt until velvety and spreadable.
  8. Layer the cooled cakes with peanut butter frosting and top with crushed Reese's Peanut Butter Cups.
  9. Chill the cake for 1 hour to ensure frosting stability before serving.