1 (18.25 ounce) package devil's food cake mix
2 cups JET-PUFFED Miniature Marshmallows, divided
4 (1 ounce) squares BAKER'S Semi-Sweet Baking Chocolate, coarsely chopped
1/4 cup milk
1 (8 ounce) tub COOL WHIP Whipped Topping, thawed
1 tablespoon unsweetened cocoa powder

Prepare and bake cake batter as directed on package for 24 cupcakes; cool completely.
Meanwhile, place 1 cup of the marshmallows, the chocolate chunks and milk in large saucepan; cook on low heat until marshmallows and chocolate are completely melted and mixture is well blended, stirring constantly. Cool at least 30 minutes. Gently stir in whipped topping.
Frost cupcakes with the whipped topping mixture; top with the remaining 1 cup marshmallows. Sprinkle evenly with cocoa. Cover and refrigerate until ready to serve. Store leftover cupcakes in refrigerator.