Instructions:
Preheat your oven according to the cake mix instructions. Grease and flour three 8-inch round cake pans.
Make the cake: In a large bowl, combine the cake mix, oil, water, and eggs (as directed). Beat with an electric mixer on medium speed for 2 minutes. Stir in the instant chocolate pudding mix until just combined.
Divide the batter evenly between the prepared cake pans. Bake for the time specified on the cake mix box, or until a toothpick inserted into the center comes out clean.
Make the peanut butter filling: While the cake layers cool, in a medium bowl, cream together the peanut butter, powdered sugar, and melted butter until smooth and spreadable.
Make the chocolate ganache: In a heat-resistant bowl, heat the heavy cream over medium heat until simmering. Remove from heat and pour over the chocolate chips. Let sit for 5 minutes, then whisk until smooth and glossy.
Assemble the cake: Once the cake layers are completely cool, place one layer on a cake plate or serving stand. Spread the peanut butter filling evenly over the top. Top with another cake layer, and repeat with the remaining filling and cake layer.
Pour the chocolate ganache over the top of the cake, letting it drip down the sides.
Decorate: Garnish with chopped Reese’s peanut butter cups. Refrigerate for at least 30 minutes before slicing and serving. Enjoy!
