INGREDIENTS
Cooking spray
2
16-to-18-ounce boxes white cake mix (plus required ingredients)
1 stick
unsalted butter, at room temperature
1 tbsp
milk
2 tsp
unsweetened cocoa powder, plus more for dusting
3
to 4 cups confectioners' sugar
2
tubs vanilla frosting
3
yellow Starburst candies
2
fresh mint leaves