Gather the ingredients - * White cake mix (+ ingredients listed on the box) * Food coloring * Vanilla pudding mix * Milk * Butter * Powdered sugar * Heavy cream * Sprinkles
Prepare cake mix according to the instructions on the packaging before dividing the batter into 4 bowls and adding a small amount of food coloring to three of the bowls, leaving one plain (I used pink, blue, and yellow here).
Add dollops of the different colored cake mix to a 9x13 pan and then gently swirl together using a toothpick.
Bake according to the directions on the packaging.
Meanwhile, prepare the pudding by mixing together the vanilla pudding mix and the milk until smooth.
As soon as the cake comes out of the oven and use a skewer to poke holes along the surface of the cake before spreading the pudding evenly across the cake.
Allow the cake to cool completely.
Prepare the frosting for the cake by beating the butter and half of the powdered sugar together until smooth in the bowl of a stand mixer fitted with the paddle attachment. Slowly add in the remaining powdered sugar along with the heavy cream and food coloring. Beat until light and fluffy.
Spread the frosting on the cake and then cover with festive sprinkles.