cookie: Mix 1 egg and 1 stick soft butter until combined. Mix in 1 box Devil's food cake until smooth Roll dough into balls and push flat onto a lined cookie sheet. Bake at 350 for 6-8 minutes. Remove to cooling rack. FILLING: Mix 1 stick butter 1T milk or heavy cream, 1/4 tsp vanilla, 1/2 tsp peppermint. Slowly add 2C powdered sugar and beat until fluffy.