Vanilla Cookies: Beat the softened butter in the bowl of a stand mixer. Mix in the eggs and vanilla. Add the cake mix and stir until a soft dough forms. Add enough green gel food coloring to achieve your desired color.

Use a 1 Tablespoon cookie scoop to place cookie dough balls on a parchment paper-lined cookie sheet about 2 inches apart.

Bake the cookies at 350 degrees for 8-10 minutes. Remove them from the oven and allow to rest for 5 minutes before transferring to a wire rack to cool.

Mint Filling: Beat the butter and marshmallow cream together in a large mixing bowl with a hand mixer. Add the vanilla and mint extracts. Mix in the powdered sugar 1 cup at a time Stir in the milk until smooth and add to a large piping bag or ziplock bag.

Cookie Assembly: Cut off the tip of the filling bag and pipe the frosting on the underside of half of the cookies. Place a second cookie on top of the frosting to make a sandwich. Enjoy!