Sideways Rainbow Cake

Sideways Rainbow Cake

This is probably the most beautiful cake I’ve ever made and I didn’t want to serve it. I had to fight the urge to keep it hidden in the back of the refrigerator. I just like looking at it. It instantly makes me happy, I mean who doesn’t love rainbows?

Sideways Rainbow Cake

The recipe and idea for this cake is from Bake It Like You Mean It. I have such a girl crush on Gesine! I love all of her books. The recipes are hard but worth the effort. I didn’t make this cake for a special occasion just a regular Saturday. I took it to work on a Monday because it is one whopping cake. I even halved the recipe in the book.

Sideways Rainbow Cake

Below is how I made the cake. If you’re interested in the full size cake and Gesine’s method check out the book. You won’t be disappointed. This cake will take a few hours to make so make sure you give yourself enough time or make the cake layers one day in advance.

Sideways Rainbow Cake

Yield: 1 big cake

Sideways Rainbow Cake



2 sticks (227g) unsalted butter, at room temperature

2 cups sugar

5 eggs

1 tsp lemon extract

3 cups flour

1 tsp salt

1/2 tablespoon baking powder

1 1/4 cups buttermilk

Gel Colors: Red, orange, yellow, green, blue and purple


2 cups icing sugar

1 pack (225g) cream cheese, at room temperature

1/4 cup (57g)unsalted butter, at room temperature

1/2 tsp vanilla


  1. Preheat the oven to 350 F/180 C and grease 3 9x9 inch pans. In the bowl of an electric mixer beat the butter and sugar until light and fluffy, about 5 minutes. Add in the eggs one at a time beating after each addition. Add in the lemon extract.
  2. In a separate bowl sift together the flour, salt and baking powder. With the mixer running on low add the flour mixture and buttermilk in three alternating batches starting with the flour and ending with the buttermilk. Don't over mix the batter.
  3. Divide the batter evenly between 6 different bowls (just under 300g in each). Use the food coloring so there is one bowl of red, orange, yellow, green, blue and purple.
  4. Use a pastry bag for each color or very carefully spoon the batter one one half of the 9x9 pans. Red and yellow in the first pan, orange and green in the second and blue and purple in the last. The colors must stay separate and not run into each other (I used a spoon and had no problems.
  5. Bake for 15-20 minutes until the tops of the cakes spring back lightly. Set aside to cool completely.
  6. Make the frosting. In the bowl of an electric mixer beat the cream cheese, icing sugar, butter, vanilla until smooth. Refrigerate for 1 hour.
  7. Once the cakes are cool using a sharp knife carefully cut each 9x9 down the center. Trim the cake so each color is exactly the same size (trim off the ends as well) save the trimmings. Line a clean baking tray with cling film (saran wrap). Place the red layer on top of the tray. Spread a thin layer of frosting on top. Stack the orange layer on top and gently press. Continue doing the same with the orange, yellow, green, blue and purple (in that order).
  8. Bring up the sides of the cling film to wrap the cake and place in the freezer for 30 minutes. Remove from the freezer and trim off the ends and sides of the cake so they are completely level (I honestly didn't do this step but probably should have).
  9. Spread a thin coat of frosting on all sides of the cake and freeze again for 30 minutes. Transfer to a serving platter. Turn the cake on it's side so the layers are vertical. Apply a thin layer of frosting to the exposed side and freeze for 10 minutes.
  10. Apply one more coat of frosting to the cake. I used some of the red trimmings and a heart shaped cookie cookie to make a heart on the top of my cake. I kept the cake in the refrigerator and on the day it was served let it come to room temperature for a few hours.


This is half the recipe from the book with my own adaptations. For the original check out Bake It Like You Mean It.

You Might Like: