What You Need
Joshua John Russell’s vanilla cake recipe (available when you start your free trial )
Joshua John Russell’s Swiss Meringue buttercream recipe (available when you start your free trial )
Joshua John Russell’s white chocolate ganache recipe (available when you start your free trial )
India Tree food coloring
India Tree sprinkles
India Tree sanding sugar
Round cake pans
Open star piping tip
Revolving cake stand
Cake leveler (optional)
Small bowls for buttercream
1. Bake the Cake
Prepare your natural vanilla cake batter as directed in the recipe. Divide it equally into four round cake pans, bake and cool completely.
Before pouring the batter into the pans, prep ’em the all-natural way: with coconut oil and flour.
2. Color the Buttercream
Whip up a batch of Swiss meringue buttercream and divide it into seven small bowls. Use the natural India Tree food coloring to dye each bowl a color of the rainbow — red, orange, yellow, green, blue, indigo and purple. You’ll have to mix some dyes together to get the colors you need.
The reason we’re adding food color to the buttercream and not the cake itself? Natural food colors change when they’re baked — blue becomes gray, yellow becomes pink, etc. By coloring the buttercream instead, we get more control and a nice, vibrant look.
Once the cakes are cooled, level the dome off the top and slice each in half to form 8 nice, flat layers.
4. Fill and Stack
Place 1 cake on a cake stand and spread 1 cup of purple buttercream across the top. Place a second cake on top and cover that in indigo frosting. Keep stacking cake and spreading buttercream until you have the rainbow filling complete. Then chill the cake until firm.
5. Add a Crumb Coat
Use a knife to shave down the cake’s sides until smooth. Then cover the entire cake with a crumb coat (a very thin layer) of white Swiss meringue buttercream. This doesn’t have to look perfect! Smooth the sides with a straight edge and chill the cake again.
6. Spread the Final Coat
Add one more (thicker) layer of white buttercream. Smooth the edges just like before. (This also doesn’t have to look perfect!)
7. Add Color
Dab food coloring onto your spatula and apply it to the cake surface in a stripe around the sides. Once all your colors are added, use a straight edge to blend and spread the color, while keeping the surface smooth, as shown in the video. As you work, move color up and down the cake to cover all the white space with an artistic, colorful finish. Scrape the top to level it when you’re done.
8. Sprinkle the Sprinkles
Mix together the India Tree sprinkles and sanding sugar in a bowl. Use your hands to press the sprinkles into the buttercream around the cake’s base. Chill the cake to make the sprinkles stick.
9. Pour On Ganache
Prepare white chocolate ganache as instructed in the recipe. Mix in food coloring and pour it over the top of your cake as shown in the video.
Only use a few drops of food coloring — enough for a pastel hue. Adding too much color can cause the ganache to become too thick for the drip effect.
10. Finish with Rosettes
Using a piping bag fitted with an open star tip, pipe Swiss meringue rosettes around the top of the cake. Then add a few more sprinkles to the top, and you’re done!