Preheat oven to 350 degrees. Cut 3 pieces of parchment paper to fit the bottoms of 3 9-inch cake pans. Spray bottoms of cake pans with baking spray. Lay a piece of parchment paper in the bottom of each and respray with baking spray. Set aside.
Melt chocolate chips in a microwave-safe bowl (heat at 20 second intervals) until smooth when stirred. Set aside.
Beat butter and brown sugar with an electric mixer until blended well, about 5 minutes.
Beat in eggs one at a time.
Beat in melted chocolate just until blended.
Sift together flour, baking soda, and salt.
Add flour mixture to batter, alternating with sour cream, beating at LOW speed just until blended after each addition.
Slowly, with mixer on LOW speed, add hot water. Batter will be liquidy.
Stir in vanilla.
Evenly distribute batter between the 3 cake pans. Bake for 22 to 25 minutes. Let cool before frosting.
Make Buttercream Frosting. Beat butter until smooth and creamy. Gradually beat in both sugar and milk. Beat in peppermint extract and food coloring.
Spread frosting on bottom layer of cake. Top with second layer and spread with frosting on the top. Top with third layer and spread remaining frosting on top.
Make ganache. Place chocolate chips in a small bowl. Place heavy cream in a small saucepan and heat just until it starts to simmer. Pour over chocolate chips. Let sit 5 minutes and then stir until smooth.
Let cool slightly and then pour over cake. Top with Andes mints