Preheat oven to 350°
In a large mixing bowl, combine the cake box ingredients using an electric mixer: cake mix, eggs, water, and oil
Place 1 cup of cake batter into a separate mixing bowl and use red food coloring to achieve desired shade (about 1 teaspoon)
Place another cup of cake batter into a third mixing bowl and use blue food coloring to achieve desired shade (about 1 teaspoon)
Prepare a bundt cake pan liberally with non-stick spray
Pour the red cake batter into the bottom of the cake pan
Pour the white cake batter over it (you will have more white cake batter than colored)
Gently pour the blue cake batter on top of the white
Bake for 40-45 minutes. We used the “toothpick test” to check that the cake was cooked all the way through
Let the cake cool for 10 minutes
Using a cooling rack or parchment paper, flip the baked cake over to remove it from the pan. It should slide right out!
Continue to let the cake cool for another hour or so
Scoop out two large spoonfuls of vanilla frosting into separate microwavable bowls: 1 for red and 1 for blue
Microwave the remaining vanilla frosting in the tub for about 15 seconds or until it is smooth enough to pour
Pour the white frosting all over the cake (as seen in the video)
Using food coloring, color the frosting you placed in smaller bowls: 1 red bowl and 1 blue
Microwave the colored frosting for 10 seconds until smooth
Drizzle the colored frosting over the cake using the spoons
Add sprinkles!