Preheat the oven to 350°f.

In a mixing bowl, combine and mix the flour, sugar, cocoa, baking soda, baking powder, and salt.

Add the egg, milk, water, oil, and vanilla. Mix until the batter is fully incorporated and smooth.

Grease two 6” cake pans with shortening or butter and then divide the batter between them.

Place the pans on a baking sheet for convenience and bake on the center rack at 350°f for 24 minutes. Test the center of the cakes with a toothpick to be sure they’re fully cooked. OR if they spring back when gently pressed in the center with your finger.

Once baked, remove and set on a wire rack to completely cool before removing the cakes from the pan. Should take about 25 minutes at room temperature.

While the cakes are cooling, combine the softened butter and peanut butter in a mixing bowl. Using a stand or hand mixer, beat until creamy and soft peaks form.

Gradually add the confectioner’s sugar and milk, alternating the two until the frosting is silky and light.

Once the cakes are fully cooled, use a cake or bread knife and slice off the domed center of the cakes making them flat-topped.

Place the bottom layer on a flat surface such as a cake plate or cardboard round.

Add a dollop of frosting and evenly spread leaving a 1/2” thickness.

Invert the other cake layer upside down and place it on top of the other frosted cake layer.

Completely frost the two layers of cake with a generous layer of frosting. Smooth the frosting as desired.

Place the frosted cake in the fridge for 30 minutes.

In a microwave-safe bowl, combine the chocolate chips and heavy cream.

Microwave for 45 seconds. Remove and mix until smooth. If the chocolate is not fully melted, microwave in 20-second intervals stirring between until the ganache is smooth.

Let the ganache cool to 90°f before adding it to the cake.

Place the ganache in a piping bag without a piping tip OR use a cake decorating squeeze bottle. Cut a very small hole in the tip. Pipe the ganache around the edge of the cake, creating small drips that flow down the side of the cake. Space them out as desired. (please see my post on the perfect chocolate ganache drip cake for detailed instructions)

Once the edge is piped, fill in the remaining cake top with the ganache. Smooth with an offset spatula.

Allow the ganache to cool and harden – should take about 15 minutes on the countertop room temperate or 10 minutes in the fridge.

Place the remaining peanut butter frosting in another piping bag with an open star tip. Pipe swirl of peanut butter frosting around the cake top evenly space.

Chop the peanut butter cups into bite-size pieces and spread them over the ganache top.

Chill until ready to serve.