This Rainbow Cake was probably the easiest kids-cake I've ever made, which is funny, because I think I was probably most anxious for how it would turn out. Not only was the birthday girl completely wrapped-up in her rainbow birthday cake, but also I was nervous about the shape of it. Even so, the birthday girl completely loved it and the shape was not a problem at all--it worked great!
To make a rainbow-shaped rainbow cake, I cooked two circular cakes, cut them in half once they cooled and stood them on end like this:
I was concerned that they would be too soft and not stand up well, so I modified the box mix recipe a bit. I had heard that beating it extra long makes the cake more dense. I figured that an extra egg would give it more stick-togetherness, and my mother-in-law (who makes wedding cakes) said that she likes to add an extra 2 Tbsp of flour to the batter to make it just a bit stiffer.
Soooo, I did all that. :)
To make the cakes stiffer:
Add 1 extra egg
Add 3 extra Tbsp flour
Beat the cake mix for 1-2 minutes longer than suggested
Now, frankly, I have no idea if any of this is even necessary, but I was going for the "better safe than sorry" philosophy here. :)
While the cakes were baking, my girls and I made frosting.
I was worried that the frosting rainbow on the front and back would just slide right off, so I decided to make decorators frosting rather than a tasting frosting. Not that decorators frosting is BAD per se, but it sure has a ton of shortening in it and therefore an awful, greasy texture. BUT, I must say, I was completely going for looks here. The kids didn't seem to think their was anything wrong with the frosting anyway. :)
1 c. shortening
4 c. powdered sugar
4 Tbsp. milk
1 1/2 tsp. vanilla
Beat it all together and you are good to go. Since a rainbow needs lots of colors, my girls and I put a large spoonful of frosting in 6 different bowls and dyed them every color of the rainbow. Then the rest we dyed a nice sky blue color.
- Place a little frosting in between each layer to get them to stick together, then frost the whole thing in blue.
- Then using a large circular open frosting tip, I made each stripe for the rainbow both on the front of the cake and the back. With the extra rainbow-colored frosting I added polka dots all over the top.
- For the clouds, I used large and small marshmallows (I cut the large ones in half because they just seemed to large) and placed them all along the bottom of the cake.
And it was done! And so cute and colorful too. :)
If you are throwing a rainbow party then you may also be interested in our Rainbow Party Printables:
And perhaps the original Rainbow Birthday Party post complete with activities and other fun party treats: