Preheat your oven to 350°F (175°C) and grease and flour two 9-inch round cake pans.

In a medium bowl, whisk together flour, baking powder, baking soda, salt, and cocoa powder. Set aside.

In a large mixing bowl, beat the softened butter, granulated sugar, and brown sugar until light and fluffy, about 3-4 minutes.

Add eggs one at a time, mixing well after each addition, then stir in vanilla extract.

Gradually add the dry ingredients to the butter mixture, alternating with buttermilk and hot water, mixing until just combined.

Divide the batter evenly between the prepared cake pans and bake for 25-30 minutes, or until a toothpick comes out clean.

Let the cakes cool in the pans for 10 minutes, then transfer to wire racks to cool completely.

For the peanut butter frosting, beat together peanut butter and softened butter until smooth, then gradually add powdered sugar and heavy cream until well combined.

For the chocolate ganache, heat heavy cream in a saucepan until simmering, then pour over chocolate chips and stir until smooth.

To assemble, place one cake layer on a serving plate, spread a layer of peanut butter frosting on top, then add the second layer.

Frost the top and sides of the cake with the remaining peanut butter frosting, then pour the chocolate ganache over the top, allowing it to drip down the sides.

Decorate as desired and serve.