Preheat the oven to 350ºF.
Mix together the cake mix, vegetable oil, and eggs until mixed.
Stir in Andes mint pieces.
Form the dough into balls and place on a greased cookie sheet.
(Optional) Place more mint pieces on top of the cookies. It'll make for prettier cookies!
Bake for about 10 minutes.
Let sit a bit before removing to a cooling rack. If topped with additional mint pieces, let completely cool before stacking- the chocolate will be soft!