Preheat your oven to 350º F.
Line cupcake/muffin pans with 24 baking cups.
Add one cookie to the bottom of each liner.
Make cake mix according to package directions and spoon cake batter into each baking cup (½ full).
Bake cupcakes according to package directions until toothpick inserted in the center comes out clean. Transfer cupcakes to a cooling rack when done.
While cupcakes are in the oven, make the frosting. Crush 6 of the cookies in a food processor.
Using a hand mixer, beat butter until creamy.
Add confectioners sugar, 3 tablespoons milk and vanilla and beat again. At this point you can add an additional tablespoon of milk if a thinner frosting is desired.
Stir in crushed cookies and refrigerate until ready to use (up to 24 hours).
Ice cupcakes once they have cooled completely.