Creating a stunning Chocolate Peanut Butter Cake is straightforward. Follow these step-by-step instructions to ensure success:

1. Preheat Oven: Begin by preheating your oven to 350°F (175°C). Prepare two 9-inch round cake pans by greasing and flouring them.

2. Mix Dry Ingredients: In a large mixing bowl, whisk together the flour, sugar, cocoa powder, baking powder, baking soda, and salt until well combined.

3. Add Wet Ingredients: Add the eggs, buttermilk, vegetable oil, and vanilla extract to the dry mixture. Mix on medium speed until thoroughly combined.

4. Incorporate Boiling Water: Carefully stir in the boiling water. The batter will be thin, which is expected.

5. Bake the Cake: Pour the batter evenly into the prepared cake pans. Bake for 30-35 minutes, or until a toothpick inserted in the center comes out clean.

6. Cool Layers: Once baked, remove the cakes from the oven and let them cool in the pans for about 10 minutes. Then, transfer them to wire racks to cool completely.

7. Prepare Frosting: In a bowl, beat together the peanut butter and softened butter until creamy. Gradually add powdered sugar, alternating with heavy cream and vanilla. Blend until you achieve a smooth, spreadable consistency.

8. Assemble the Cake: Once the cake layers have cooled, place one layer on a serving plate. Spread a generous amount of peanut butter frosting on top.

9. Add Second Layer: Carefully place the second cake layer on top and spread frosting over the top and sides of the cake.

10. Decorate: Finally, garnish with chopped peanuts or chocolate shavings for an elegant touch.

Now, your Chocolate Peanut Butter Cake is ready to be enjoyed!