1Heat oven to 350°F (325°F for dark or nonstick pans). Place paper baking cup in each of 24 regular-size muffin cups.
2Make cake as directed on box for 24 cupcakes--except fill muffin cups half full; top each with 1/4 teaspoon sprinkles. Top with remaining batter; sprinkle each with 1/2 teaspoon sprinkles.
3Bake as directed on box for cupcakes. Cool in pans 10 minutes; remove from pans to cooling rack. Cool completely, about 30 minutes.