1 pkg. (2 layer size) devil's food cake mix
20 Oreo Cookies, divided
3 cups thawed Cool Whip, divided
2 1/2 cups Jet Puffed Miniature Marshmallows, divided

Prepare and bake cake mix in 2 (9 inch) round cake pans as directed on package, and let cool completely. Coarsely chop 10 of the cookies. Add 2 cups of the whipped topping in large bowl along with 1 1/2 cups of the marshmallows; stir gently until well blended. Place on cake layer on serving dish, spread with whipped topping mixture. Cover with second cake layer. Frost top with remaining 1 cup whipped topping. Refrigerate until read to serve. Garnish with remaining 10 cookies and 1 cup of marshmallows just before serving.