Preheat the oven to 350 degrees F. Line two cookie sheets with parchment paper and set aside.

Mix cake mix, oil, and eggs in a large bowl until well combined. Drop the cookie dough onto the prepared cookie sheets using a medium cook scoop (about 2 tablespoons), leaving at least 2 inches between each cookie.

Bake for 10-12 minutes or until the edges of the cookies are set. Allow the cookies to cool on the sheet for 5 minutes before transferring them to a wire rack to finish cooling.

Beat the butter in a large mixing bowl with an electric mixer until smooth. Add the powdered sugar, 2 tablespoons of milk, peppermint extract, salt, and 4-5 drops of food coloring and beat until smooth. Add additional milk 1 teaspoon at a time, and a few drops of food coloring until the desired consistency and color is reached.

Spread a layer of the green frosting over the cookies with an offset spatula or butter knife.

Add chocolate chips to a small microwave safe bowl. Pour 1/3 cup of heavy cream over the chocolate chips and microwave for 45 seconds. Allow the bowl to rest for 1 minute before whisking the chocolate and cream to form the ganache.

Set the the ganache aside to cool for 10-15 before spreading a heaped spoonful on each cookie.

Allow the ganache to set before serving or storing the cookies.