Preheat Your Oven: Start by preheating your oven to 350°F (175°C) and greasing & flouring two 9-inch round cake pans.
Prepare the Cake Batter: In a large mixing bowl, combine 1 3/4 cups all-purpose flour, 2 cups granulated sugar, 3/4 cup cocoa powder, 2 tsp baking powder, 1 1/2 tsp baking soda, and 1 tsp salt. Stir these dry ingredients until well mixed. Next, add 2 large eggs, 1 cup of milk, 1/2 cup of vegetable oil, and 2 tsp of vanilla extract to the dry mix. Finally, carefully stir in 1 cup of hot water until combined. The batter will be thin, but that’s okay!
Bake the Cake: Divide the batter evenly between the two prepared cake pans. Bake in the preheated oven for 30-35 minutes, or until a toothpick inserted into the center comes out clean. Once done, remove the pans from the oven and allow the cakes to cool completely in the pans before transferring to a wire rack.
Make the Peanut Butter Frosting: In a large mixing bowl, beat 1 cup of softened unsalted butter and 1 cup of creamy peanut butter together until smooth. Gradually add in 4 cups of powdered sugar and 1/4 cup of heavy cream, mixing until the frosting is fluffy and well combined.
Prepare the Chocolate Ganache: In a small saucepan over medium heat, heat 1/2 cup of heavy cream until just simmering. Remove from heat and pour over 1 cup of dark chocolate chips in a bowl. Let it sit for about 2 minutes, then stir until smooth and glossy.
Assemble the Cake: Place one cake layer on a serving plate. Spread a layer of peanut butter frosting over the top, then add the second cake layer on top. Pour the chocolate ganache over the top, allowing it to drip down the sides. Finally, top with mini Reese's Cups and a sprinkle of crushed peanuts for decoration.