Make and bake two round cakes from the cake mix or make your own favorite chocolate cake recipe. Cool cakes.
When cakes are cool, you will mix the whipped white frosting with one sleeve of coarsley chopped thin mint cookies (you can also use the off brand if it isn't girl scout cookie season). You can add in some mint extract to the frosting mixture if you so desire for an even mintier flavor, I used half a teaspoon. You will spread a thick layer of the frosting/cookie mixture over one of the cakes and then layer the other cake on top.
Now you can frost the whole cake with the chocolate frosting. Feel free to garnish the cake any way you like. I crushed more of the cookies and put them on the side of the cake.
I used a boxed cake mix and canned frosting but if you have favorite from scratch recipes you could easily use those.