Step 1

Position oven rack in the center of the oven. Preheat to 350°F (177°C). Generously spray two 9-inch cake pans with nonstick spray. Line the bottom of the pan with Oreos in a single layer; I fit about 15 Oreos in each pan. Set aside.

Step 2

In a large bowl, using a handheld or stand mixer fitted with a paddle attachment, blend the cocoa powder, sugar, cake flour, baking soda, and salt together on low speed for 30 seconds. Add the eggs, oil, sour cream, and vanilla and mix for 1 minute on medium-low speed.

Step 3

Remove the bowl from the mixer and add the coffee and chocolate chips; stir to combine. Some of the chocolate chips will melt as you stir. Try to avoid over mixing the batter.

Step 4

Pour the batter into the prepared cake pans over the Oreos. Bake for 28-32 minutes or until a toothpick inserted in the center of the cakes comes out clean. Allow cakes to cool completely in the pan on a wire rack.

Step 5

While the cake cools, make the Oreo Cream Filling. In a large bowl, using a handheld or stand mixer fitted with a paddle attachment, cream the butter and shortening together on high speed until fluffy. Add the confectioners’ sugar, 1 cup at a time, alternating with the milk/cream and vanilla. The filling will be very thick, but you may add more milk/cream if you prefer. Set aside in the refrigerator.

Step 6

While the cake cools, make the Chocolate Buttercream. In a large bowl, using a handheld or stand mixer fitted with a paddle attachment, cream the butter on high speed until fluffy, about 1 minute. Beat in the cocoa powder and vanilla on low speed, then add the confectioners’ sugar 1 cup at a time, alternating with the milk/cream. The buttercream will be thick. Set aside in the refrigerator.

Step 7

Once the cakes are cooled, assemble the cake. Place 1 cooled layer on a cake stand or large plate, Oreo cookie side down. Using an offset spatula or knife, cover the top with a 1-inch thick layer of Oreo Cream Filling. Top with the 2nd cake, Oreo cookie side up. Cover the tall layer cake with chocolate buttercream. Working quickly, cover the cake in Oreo crumbs. This will get a little messy, but just pat them up the sides with your hands and all over the top of the cake.

Step 8

Slice and serve cake. Leftover cake can be covered and stored in the refrigerator for up to 3 days.