1 box Betty white cake mix
cup butter, melted and slightly cooled
3 eggs
1 teaspoon vanilla
3 tablespoons Betty Crocker™ Decorating Decors rainbow mix
Frosting:
1 cup butter, softened
3 cups powdered sugar
2 to 3 tablespoons milk
1 teaspoon vanilla
Assorted candy sprinkles
Heat oven to 350°F. Grease bottom of 13x9-inch pan with shortening or cooking spray. In large bowl, beat sugar cookie mix, cake mix, melted butter, eggs and 1 teaspoon vanilla with electric mixer on low speed 30 seconds. Beat on medium speed about 1 minute or until blended. Stir in 3 tablespoons candy sprinkles. Spread in pan. Bake 32 to 34 minutes or until golden brown. Cool completely, about 1 1/2 hours. In large bowl, beat 1 cup softened butter, the powdered sugar, 2 tablespoons milk and 1 teaspoon vanilla until combined. Add additional milk 1 teaspoon at a time until spreading consistency. Spread over cooled bars. Sprinkle with assorted candy sprinkles. Cut into 6 rows by 4 rows.