1Heat oven to 350°F (325°F for dark or nonstick pans). Make, bake and cool cake mix as directed on box for 24 cupcakes.
2To make chocolate curls, pull a swivel-bladed vegetable peeler down the edge of white chocolate bar, using long, thin strokes. Frost cupcakes with frosting. Sprinkle each with about 2 teaspoons white chocolate curls, using toothpick to lift curls.
3Lightly sprinkle powdered sugar through small strainer over cupcakes. Store loosely covered.