Yield: Serves 20 to 30

Time: 2 hours total

Note: We tested the cake in the Test Kitchen using Betty Crocker Super Moist White Cake Mix and 9-inch cake pans.

Ingredients

4 (16.25-ounce) boxes white cake mix (enough for 8 cake layers)

5 cups 7-Up or similar soda, divided, to substitute for the water in the cake mix

1 1/3 cups vegetable oil, divided, or as needed to prepare boxed cake mix

12 egg whites, divided, or as needed to prepare boxed cake mix

Assorted food coloring

About 20 cups (10 pounds) prepared white frosting

24 packets assorted Pop Rocks

Candy wax soda bottles, for decorating

Skewers, for decorating

Soda straws, for decorating

Procedure

1. Prepare the boxed cake mix according to the manufacturer's instructions, substituting soda for the amount of water given and incorporating the vegetable oil and egg whites as instructed (cake mix ingredients may vary slightly by brand). Divide the cake mix among prepared 8- or 9-inch cake pans (you will end up with one extra layer of cake not needed for this recipe). Add food coloring to enhance each of the seven layers separately with bright color: turquoise, pink, yellow, orange, purple, aqua, lime. Bake according to the manufacturer's instructions.

2. When the cake layers are cool, begin assembling the final cake. Place the first layer on the cake stand or platter and top with a layer of frosting. Sprinkle over a packet of Pop Rocks. Top with a second layer of cake, and repeat until the cake is seven layers. As the layers are built, the cake will become top-heavy and may start to slide and/or fall; to help stabilize the cake, run skewers or cake dowels (available at cake and cooking supply stores) through the layers.

3. Frost the outside of the layers and sprinkle over the remaining Pop Rocks to decorate. (Note: The Pop Rocks will become sticky shortly after the package is opened and if handled. To decorate the sides, it might be easiest to empty each package onto a sheet of paper, then curl the paper and blow the Pop Rocks onto the side of the cake.)

4. To assemble the decorations, place the wax soda bottles on skewers and cover each skewer with a soda straw. Arrange the bottle-topped skewers on top of the cake to decorate.

Each of 30 Servings

Calories: 910

Protein: 3 grams

Carbohydrates: 166 grams

Fiber: 1 gram

Fat: 25 grams

Saturated fat: 6 grams

Cholesterol: 0

Sugar: 128 grams

Sodium: 747 mg