Mix all ingredients except marshmallows together. Spread cookie mixture evenly in bottom of ungreased 13" x 9" pan. Bake at 350° for 15 to 20 minutes. Remove from oven, and top with mini marshmallows. Return pan to oven, and bake an additional 5 minutes or until marshmallows begin to melt. Cool in pan; ice with Chocolate Frosting.