These are one of our favorites at our house. Lately my daughter has been begging for them, so last night, we made 'em.
2 boxes of Devils Food cake mix
2/3 cup oil
Mix together. Roll into balls. Bake at 350 for 8-10 minutes. They're done with the tops start to crack.
1/2 cup butter
4 oz cream cheese
2 cups powdered sugar
2 tsp mint extract (or desired amount for the flavor you like)
a few drops green food coloring
Once cookies have cooled, spread desired amount frosting on one cookie, then add another cookie on top to make a sandwich.