Preheat oven to 350°F. Grease and line three 8-inch cake pans.
In a large bowl, whisk flour, sugar, cocoa powder, baking soda, baking powder, and salt.
Add buttermilk, hot water, oil, eggs, vanilla, and peppermint extract. Mix until smooth.
Fold in mini chocolate chips. Divide batter evenly among pans.
Bake for 23-26 minutes or until a toothpick comes out clean. Let cool completely.
For the frosting: Beat butter until creamy. Gradually add powdered sugar, peppermint extract, and cream.
Add green food coloring, if desired. Beat until fluffy.
For the ganache: Heat cream and pour over chocolate chips. Let sit 2 minutes, then stir until smooth. Cool slightly.
Assemble the cake by layering with mint frosting. Spread frosting over the top and sides.
Pour ganache over the cake and top with chopped Andes Mints.