Rainbow Tie-Dye Cake with a Secret

Ingredients:

Chocolate sponge cake numbers

• 1 package 432 gr. dry chocolate cake mix
• 1 package of 100g dry chocolate pudding mix
• 1.5 cups of milk
• 1 cup sour cream
• 0.5 cups vegetable oil
• 4 large eggs

Tie-dye cake

• Cooking spray
• 1 package 432 gr. dry mix for white cake
• 1 package of 100g dry white chocolate pudding mix
• 1.5 cups of milk
• 1 cup sour cream
• 0.5 cups vegetable oil
• Protein of 6 eggs (180 g liquid egg whites)
• Purple, royal blue, sky blue, green, yellow, orange, and red food coloring

Glaze

• 2 cups powdered sugar
• 1 cup vegetable fat (margarine)
• 1/4 cup heavy whipping cream
• 1 tsp vanilla extract
• 1 can 367 gr. creamy marshmallows, for example, Fluff

Rainbow glaze

• 90 g white Candy Melts or white chocolate, finely chopped
• 3 tablespoons heavy whipping cream
• 1.5 tbsp corn syrup
• Purple, royal blue, sky blue, green, yellow, orange, and red food coloring
• Special equipment: A 12 x 5-inch loaf pan, 1.5-inch number cookie cutters, a wooden dowel, disposable pastry bags or large zip-lock plastic bags, and a cake stand

Preparation:

1. Chocolate sponge cake numbers:

   
   Preheat oven to 350°F (175°C). Line a 12 x 5-inch loaf pan with aluminum foil. Spray the pan with cooking spray.
   
   In a bowl, combine the chocolate cake mix, chocolate pudding mix, milk, sour cream, butter, and eggs. Using a mixer, beat on low speed for 30 seconds, then beat on medium speed for 2 minutes. Pour the batter into the prepared pan.
2. Bake until a toothpick inserted into the center comes out clean, 52-58 minutes. Cool the cake in the pan for 10 minutes, then remove and transfer to a wire rack to cool completely.
3. Trim off the puffed top of the cake and about 0.5 cm from each end. Cut the cake into 13 equal slices. Freeze the slices for 1 hour. Remove the cake from the freezer, place it on a cutting board, and cut out number-shaped cakes using cookie cutters. To remove the cake from the cutter, gently push the pieces out with a wooden skewer.
4. To make a sixteenth birthday cake, cut out the numbers 1 and 6 from each piece of cake. Line a baking sheet or cutting board with a silicone mat, foil, or parchment paper. Place the numbers on top, cover, and freeze for at least one hour.

5. Tie-dye cake:

   
   Once the numbers are frozen, mix up the colored cake batter. Line a 12 x 5-inch loaf pan with aluminum foil. Spray the pan with cooking spray.
   
   In a bowl, combine the white cake mix, white chocolate pudding, milk, sour cream, vegetable oil, and egg whites. Using a mixer, beat on low speed for 30 seconds, then beat on medium speed for 2 minutes. Divide the batter evenly among 7 bowls. Add purple food coloring to one bowl, royal blue to another, light blue to a third, green to a fourth, yellow to a fifth, orange to a sixth, and red to a seventh. Transfer each colored batter to a disposable pastry bag or a large zip-lock plastic bag. Snip the corner of each bag. Pipe squiggly shapes of purple batter onto the bottom of the prepared pan, leaving space between the squiggly shapes for the other colors. Pipe the next color of batter, and so on, until all 7 colors have been piped onto the bottom of the pan.
6. Remove the biscuit numbers from the freezer. If the numbers have holes, pipe two different colors of dough into them, filling the hole two-thirds full. Pipe a very thin layer of dough along one of the short sides of the pan.
7. Press the numbers vertically onto the dough. Press the following numbers vertically onto the first ones until you've lined them all up along the mold. If you have more than one number, pipe squiggles of colored dough between them, alternating colors to your liking. Press squiggles of colored dough around the outside of the numbers, alternating colors.
8. Then, using alternating colors, press squiggles of colored dough over the numbers. Smooth the cake surface. Do not disturb the colored dough in the pan. Tap the pan on the counter 5 times to release any large air bubbles.
9. Cool in the pan for 10 minutes, then remove from the pan and transfer to a wire rack to cool completely. Trim the domed top of the cake and about 0.5 cm off each end. Trim the thin crust off each long side of the cake. Freeze it to firm up, if desired. Place the cake on a cake stand that is at least 0.5 cm taller than the cake on all sides. Mark one end of the stand. Stand the cake so the numbers face the mark.

10. Glaze:

    
    Beat the powdered sugar, shortening, whipping cream, vanilla, and marshmallow cream until light and fluffy. Frost the cake.
    
    

    Rainbow Glaze:

    
    In a microwave-safe bowl, combine the finely chopped candy melts, whipped cream, and corn syrup. Microwave on high power in 15-second intervals, stirring until melted. Divide the frosting evenly among 7 small bowls. Add purple food coloring to one bowl, royal blue to another, light blue to a third, green to a fourth, yellow to a fifth, orange to a sixth, and red to a seventh.
11. Let the icing thicken slightly. Create a melting rainbow by dripping colored icing down the side of the cake, starting with purple, then royal blue, light blue, green, yellow, orange, and red.
12. Position the cake stand so you know which side the numbers are facing. Stand back and watch as the birthday boy or girl cuts the first slice of cake. Everyone will be delighted to see the numbers appear on the rainbow sponge.