Preheat oven to 350 degrees. Grease and flour 2 round 9-inch cake pans.
For the cake, put flour, sugar, cocoa, baking powder, baking soda and salt in a bowl and mix well.
In a stand mixer, mix the buttermilk, oil, eggs, vanilla together. Slowly add in the mix of dry ingredients while the mixer is on low. Add the coffee and make sure everything is combined. Batter will be very thin.
Pour the batter into the prepared pans and bake for about 25 minutes or until a toothpick inserted in the middle comes out clean.
Turn the cakes out onto a cooling rack. While the cakes are cooling, make your frostings.
Cream together the butter and sugars in a stand mixer until smooth and creamy.
Add the flour, milk and vanilla and beat on high until well combined, about 2-3 minutes.
Now it's time to put together your cake!
Frost the top of the first cake with the Cookie Dough Frosting. Then layer the other half of the cake on top. Frost the outside of the cake with the Chocolate Buttercream Frosting.
Pipe dollops along the bottom edge and top with the leftover Cookie Dough Frosting and/or decorate as desired. Top with a chocolate chip cookie!
Video
Notes
You can easily substitute a boxed cake mix and store-bought chocolate icing in order to save some time!