Fudgy Fireworks Brownies

Heat oven to 350°F. Line 13x9-inch pan with foil, letting foil hang 2 inches over sides of pan. Spray foil with cooking spray.

Make brownie batter as directed on box for cakelike brownies. Stir in chocolate chips and vanilla baking chips. Spread in pan. Bake 22 to 25 minutes or until toothpick inserted 2 inches from side of pan comes out almost clean. Transfer to cooling rack to cool completely in pan, about 1 hour.

Using foil to lift, remove brownies from pan, and peel foil away. Turn out onto cooling rack so bottom is now top; place over cookie sheet or waxed paper.

In small microwavable bowl, microwave frosting uncovered on High 20 to 30 seconds or until thin enough to pour. Place 3 tablespoons warmed frosting into each of 2 small bowls. Tint 1 bowl red, 1 bowl blue by stirring in each food color to desired color. Set aside.

Pour remaining vanilla frosting to cover top of brownie. Using icing spatula, smooth frosting over top, pushing toward edges, trying to spread as little as possible to keep surface smooth. Sprinkle 1 teaspoon candy sprinkles on top.

Rewarm bowls of colored frosting in microwave 5 to 10 seconds to maintain pouring consistency, if needed. Spoon about half tablespoon of each colored frosting onto top of glazed brownie. Using tip of spoon, pull frosting out from center of circle in random splatter pattern to look like fireworks. Repeat with remaining colored frosting. Sprinkle remaining teaspoon of sprinkles over colored frosting. Cool 30 minutes.

Cut into 6 rows by 4 rows. Store in airtight container at room temperature.