1On work surface sprinkled with powdered sugar, roll fondant to 1/8-inch thickness. With 2-inch bone-shaped cookie cutter, cut 48 bones from fondant, rerolling as needed. Place bones in single layer on ungreased large cookie sheet; let dry uncovered at least 6 hours or overnight.
2Heat oven to 350°F. Place paper baking cup in each of 24 regular-size muffin cups. Make and bake cake mix as directed on box for cupcakes, using water, oil and egg whites. Cool 10 minutes; remove cupcakes from pans to cooling racks. Cool completely.
3Spoon frosting into resealable food-storage plastic bag or decorating bag fitted with metal tip #1G. If using plastic bag, seal bag and cut off small corner. Pipe frosting on cupcakes. Sprinkle with cookie crumbs. Place 2 fondant bones on each cupcake to look like crossbones.