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.

Make the Chocolate Buttercream .

Mint Buttercream:

In a stand mixer bowl, use the paddle attachment to cream butter on medium speed until the butter is fluffy and almost white. This will take about 2-3 minutes. Scrape down the sides and mix in the mint and vanilla extracts. Add in powdered sugar and heavy cream. Mix on low speed until combined. Add in the green food coloring and beat on medium-high for 2-3 minutes until light and fluffy.

Now it's time to put your cake together!

Put down one layer of chocolate cake. Spread the mint buttercream on top of the cake. Place the second chocolate cake on top of the frosting. Frost the top and sides of the cake with the chocolate buttercream.

Place grasshopper cookies around the outer edge of the cake, pressing down slightly so they stay in place.

Place Wilton tip 2D in a decorating bag. Fill it with mint buttercream and pipe stars around the bottom edge of the cake. Then pipe a star on the top of each grasshopper cookie.

Lastly, make a swirl of buttercream in the center of the cake.

Place a chocolate chip on each star, if desired, then sprinkle additional chocolate chips on the swirl that is in the center of the cake.