Preheat oven to 350 degrees F. Prepare cake batter as directed on package; set aside.
Mix cream cheese, egg and sugar until well blended.
Spoon cake batter into each of 24 paper- or foil-lined medium muffin cups, filling each cup about half full. Top each with about 1/2 Tbsp. of the cream cheese mixture and 1 cookie. Cover evenly with remaining cake batter.
Bake 19 to 22 min. or until toothpick inserted in center comes out clean. Cool 5 min.; remove from pans to wire racks. Cool completely. (There may be an indentation in top of cupcake after baking.) Top cupcakes with whipped topping and remaining cookies just before serving.
