I had this idea for a cake for a while now, and it finally cooled off so I could bake the other day. It's a rainbow cake, tie-dye style; a super-fun and easy way to decorate a cake for that little extra special occasion!  Where's the tie-dye you ask? Underneath all that icing! (By the way, we used a swiss meringue buttercream for this recipe. Once you learn how to make this icing, you'll never go back. I love the consistency of this icing. So so smooth.

Check out the how-to below (and check out the video also at the bottom of the post to see how it all was made.





Tie-Dye Rainbow Cake

This recipe uses half a cake recipe (one 9" round cake pan) or feel free to make two cakes (or one full cake recipe)! The perfect size for 4 to 5 people.

Ingredients
1/2 one white cake recipe or box mix of your choice.
rainbow coloured food colouring

Mix the white cake mix according to directions. Separate evenly into 5 different bowls. Add a different colour (choosing rainbow colours) to each bowl (eg. pink, orange, yellow, green, blue). Pour the batter starting with the blue into a well greased/floured pan. Then add the green, followed by the yellow, then orange and finally pink (see image below for how it should look - tie-dye syle). Bake for approximately 20 minutes or until done.  Let cool.



While the cake is baking, make the icing!
This is a swiss meringue buttercream. Once you learn how to make this icing, you'll never go back. I love the consistency, so smooth like butter!

Swiss Meringue Icing
To make this icing, you'll need something that resembles a bain marie. A pot on the bottom to bring the water to a boil and a bowl that will easily sit atop of the pot, and something you're still able to grab.

Ingredients
5 egg whites
1 cup (and 2 tablespoons) of white sugar
a pinch of salt 
2 tsp. to 1 tablespoon vanilla (to taste)
1 pound (4 sticks) room temperature unsalted butter (cut into 1 tablespoon size pieces).

How to
Start the water to boil in the pot. Once it comes to a boil, turn down to simmer.  In the bowl, add the 5 egg whites, the sugar and the salt. With the bowl placed atop of the pot, start to beat the egg whites, dissolving all of the sugar as you go.  This takes approximately 3 minutes.  Remove from heat.  Continue to beat until peaks start to form in the egg whites and when the bowl is cool to touch. This takes approximately 7 - 10 minutes.

Slowly start to add the butter, one tablespoon at a time, until it is well incorporated. Continue mixing until all the butter has been added. Add the vanilla at the end. Mix well. Separate the icing into 5 or 6 different bowls. Add a different colour (choosing rainbow colours) to each bowl (eg. pink, orange, yellow, green, blue, etc). And then transfer the icing into icing bags - using the star tip.

To Make the Rainbow
Cut the cake in half. And layer on top of each other - icing in between to keep them together. Place the half circles upright so they look like a rainbow once standing.  Give the cake a crumb coat of icing, then chill until set.  Pull the cake out of the fridge and start to star tip a basic rainbow onto the sides of the cake. To help me make it even, I drew out each rainbow colour using a knife. Begin to ice. I started with pink, then onto orange, yellow, green and then blue. Cover the entire cake and it's ready! Check out the video at the bottom of this post (or on our instagram) to see how we cut it! Happy tie-dye rainbows!