PREPARE cake batter as directed on package. Blend in 1/4 cup (4 Tbsp.) dry drink mix. Pour into 24 paper-lined muffin cups.
BAKE as directed on package for cupcakes; cool in pans 10 min. Remove to wire racks; cool completely.
MIX remaining drink mix with frosting in medium bowl until well blended. Gently stir in COOL WHIP. Spread onto cupcakes. Keep refrigerated.