Preheat your oven to the temperature specified on the boxed cake mix. Grease a 9x13 baking dish with nonstick cooking spray and set it aside.

In a medium-sized bowl, follow the instructions on the back of the cake mix to prepare the batter. Divide the batter into four bowls and add a few drops of food coloring to each bowl without mixing the colors.

Stir the batter and food coloring in each bowl until you achieve the desired color. Using a spoon, quickly drop small dollops of each colored batter into the prepared baking dish. Due to the greased dish, the drops will spread, so work efficiently.

After adding all the batter, lightly tap the bottom of the dish on the counter. Use a toothpick to gently swirl the colors without overmixing. Bake according to the cake mix instructions.

Once baked, allow the cake to sit for about 10 minutes. Then, poke the top of the cake all over with the end of a wooden spoon or a large straw, approximately an inch apart. Let the cake cool completely.

In a large bowl, whisk together white chocolate pudding mix and milk until fully dissolved. Pour the pudding mixture over the cooled cake, spreading it with a spatula to ensure it fills the holes. Refrigerate for 30-40 minutes until the pudding sets.

In another large bowl, combine heavy cream and vanilla extract. Use a hand mixer to beat until soft peaks form. Add powdered sugar and continue mixing until stiff peaks form, taking about 5-6 minutes. Once the pudding layer is set, spread the whipped cream over the top of the cake.

Optionally, decorate with sprinkles on top of the whipped cream. Slice and serve your delicious cake!