Preheat your oven to 350°F and line a 13"x18" half-sheet pan with parchment paper. Set it aside.

Prepare the cake mixes according to the instructions on the box, adding 6 eggs, 1 cup of oil, and 2 cups of water.

Divide the batter evenly into 5 bowls and color each one with a different food coloring of your choice. I used pink, orange, yellow, green, and blue.

Transfer each colored batter into a separate large pastry bag.

Cut the tips off each pastry bag and pipe the batter onto the prepared pan in straight lines, alternating colors. Each line should be about 13 inches long. Once all the batter has been piped, take a toothpick and gently insert it into the center of the batter. Drag it out to the outer edge and back toward the center, creating a spoke-like pattern—this will give the cake a tie-dye effect.

Bake the cake for 25 minutes. Let it cool completely, then refrigerate for 2 hours. Afterward, use a cake cutter to cut out three 6-inch round layers.

Place the first layer on a cake plate, pipe dollops of frosting on top, and spread it out to cover the layer. Repeat this process with the remaining two layers. Do not frost the sides of the cake. Your cake is now ready to serve!

Beat the softened butter on medium speed using an electric or stand mixer for about 3 minutes, until smooth and creamy.

Add the powdered sugar, heavy cream, and vanilla extract while the mixer is running on low. Once everything is incorporated, increase the speed to high and beat for an additional 3 minutes.

Transfer the frosting into a large pastry bag fitted with a large round pastry tip.

Note: If the frosting is too thick, you can adjust the consistency by adding a tablespoon of cream at a time. Mix thoroughly after each addition until you reach your desired texture.

What to Do with Leftover Cake

If you have leftover cake and frosting, don't worry! You can cut the extra cake into small squares or circles and pipe frosting on top to create mini cakes. You should be able to make around 12 mini square or circular cakes.