Surprise Rainbow Cake

This rainbow cake has been on my to-do list for quite some time and since St. Patrick’s Day is coming up I thought it’d be perfect to try it out now.

Crayola vibrant colors. 4-8 drops of gel food coloring for each color weighing in at 9 oz. of batter

A LOT of butter. 4 sticks just for the frosting.

Tackling swiss meringue buttercream frosting for the first time. A lot of the reviewers mentioned “soupy” frosting. Egg whites beaten to soft/stiff peaks and then add butter. The frosting looks like this cottage cheese mess. Then you switch to a paddle attachment and whip it for about 5 minutes and it becomes a glossy buttercream.

Cake ready to assemble! Purple layer…

Blue layer…

Green…etc. You get the idea.

Voila!

All covered. I like that its a surprise as to what is inside. It’s going to be left rustic because I just couldn’t make any more frosting.

I didn’t freeze any of the cakes but everything was room temp before assembling. The first slice was not hard to take out.

Before tackling this project, note it was 4 hours with two extra helpers (thanks Sarah and Janet!)

Rainbow Cake
from Whisk Kid blog and featured on marthastewart.com

My notes:

• I used 9″ cake pans so the cake layers were very thin (1/2″) and fragile. I would recommend 8″ or even smaller if you want thicker layers. If you use spring form pans, line them with parchment because the batter did leak under.
• To make sure I had an even amount of batter for each color, I weighed the bowl with the batter (84 oz) and subtracted out the weight of bowl (27 oz- Kitchen Aid 4 qt metal bowl). So for each color it was 9 oz of batter.
• I used Ateco gel food coloring. 4-8 drops per color.

Lemony Swiss Meringue Buttercream
from marthastewart.com

My notes:

• RECIPE: There are two recipes- one for filling the cake + crumb coat and another for the final coat. The first recipe has 9 egg whites + 4 sticks of butter. At this point I’ve used 5 egg whites + 2 sticks of butter in the actual cake so the total = 14 egg whites + 6 sticks of butter. A lot yes. I couldn’t stand the thought of doing the 2nd recipe unless absolutely necessary, so the cake didn’t get beautified as I’d had wanted.
• LEMON: Calls for one teaspoon. I think it could have been a little stronger or maybe added to the cake as well. I’d add another 1/2 teaspoon.
• EGG WHITES: I bought a pint carton of egg whites for this recipe so I wouldn’t end up with a ton of egg yolk.
• WHIPPING: When whipping the heated egg mixture, the recipe says to do so until it reaches room temperature. The important part is to whip to soft peaks and also make sure the mixture is cooled enough. I mixed for about 8 minutes until it stopped steaming. The bottom of the bowl was still slightly warm but not hot.
• CURDLING: Once the egg whites are at soft peak, add the butter one cube at a time. The mixture did become soupy.
• CREAMING: Switch to a paddle attachment and whip the soup mixture for 5 minutes and it will turn into a frosting.