Preheat oven to 350 degrees F. Coat two 8-inch round cake pans with cooking spray. Pour batter into prepared baking pans and bake according to package directions. Let cool to room temperature. Place 2 to 3 drops of food coloring into 1 container of frosting. Mix well.
Place one cake layer upside down on a serving platter. Spread half of white frosting over top of cake. Place second layer over first and frost sides with blue frosting. Spread remaining white frosting on top of cake. Arrange candy coated chocolates and pretzel sticks on sides of cake as shown in photo. Place lollipops on top of cake.