Heat oven to 350°F. Spray three 8-inch round cake pans with baking spray with flour.
In a large bowl, whisk together the dry ingredients: sugar, flour, cocoa, baking soda, baking powder and salt. In another bowl, add the wet ingredients: eggs, buttermilk, coffee, oil, and vanilla.
Using a hand-held mixer on medium speed, mix the wet ingredients until combined. Add the dry ingredients to the wet ingredients and mix until incorporated.
Divide batter evenly among prepared pans. Bake for 30 to 35 minutes or until centers are set and a wooden pick inserted into the center of the cakes comes out clean.
Let cakes cool in pans for 10-15 minutes, then turn out onto a wire rack until completely cooled.
For the frosting
In the bowl of a stand mixer, cream butter and shortening together until smooth and creamy. Add peppermint extract and heavy cream. Mix until incorporated.
Add powdered sugar two cups at a time, starting on low until mostly combined, and medium-high until completely combined. Scrap the sides of the bowl between each addition.
Add gel food coloring, starting with a small amount and adding more until the desired color is reached.
When cake layers are cool, place one layer on a cake plate or stand. Cover with frosting; repeat with the other two layers. Spread frosting around the outside of the cake. Pipe any remaining frosting on the top of the cake and garnish as desired.