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

Mix Dry Ingredients: In a large bowl, combine the flour, cocoa powder, sugar, baking powder, baking soda, and salt.

Mix Wet Ingredients: In another bowl, beat the eggs, milk, oil, and vanilla extract until well blended.

Combine Ingredients: Gradually add the wet ingredients to the dry ingredients, mixing until just combined. Stir in the boiling water until smooth; the batter will be thin.

Bake the Cake: Divide the batter evenly between the prepared pans. Bake for 30-35 minutes or until a toothpick inserted into the center comes out clean. Let the cakes cool in the pans for 10 minutes, then remove from pans to wire racks to cool completely.

Prepare Peanut Butter Layer: Spread 1 cup of peanut butter evenly over the top of one cooled cake layer.

Chocolate Ganache: In a small saucepan, heat the cream until just boiling. Pour over chocolate chips in a bowl, let sit for a minute, then stir until smooth.

Assemble the Cake: Place the second cake layer on top of the peanut butter-spread layer. Pour the chocolate ganache over the top, letting it drip down the sides.

Decorate: Drizzle with chocolate sauce. Sprinkle chopped mini peanut butter cups and crushed peanuts on top. Optionally, drizzle additional creamy peanut butter for extra decadence.