Raspberry Lemon UNICORN Cake

Updated: Aug 28, 2020

Have you noticed this whole sheet cake slash snacking cake trend take over Instagram? I don't understand because in my opinion every cake is a snacking cake. But I do appreciate how EASY it is to make a beautiful one layer cake with frosting. Much less fussy than trying to vertically decorate a layer cake and moving it around on a cake spinner. On a sheet cake I'm only working in 2D on a flat surface. It's the perfect opportunity to play with frosting tips and colors!

I'm not very good at piping with frosting. I never had the patience for it. But this is Baking With Chickens and the entire purpose of this blog is to go out of my comfort zone and push myself to do things that I previously told myself that I wasn't good at doing. You guys. This cake turned out SO GOOD!!!!!!

Choosing a Cake Base

Like most recipes I usually start with what's in my fridge that need to be used before it goes bad. In this case I had raspberries and sour cream as my base inspiration. I wanted a super light, fluffy cake that wasn't too sweet or too dense. A few clicks later I found this Raspberry Lemon Cake recipe from The View From Great Island. A few notes on adjustments I made to the recipe:

Substituted sour cream for the Greek yogurt
Tossed the raspberries in flour before folding them into the cake batter to help suspend them in the cake. Remember my tip from Strawberry Banana Bread?
Added grated lemon zest to the dry ingredient phase and a couple drops of lemon extract.
Omitted the lemon buttercream in favor of a lemon Swiss buttercream recipe from King Arthur Flour.

The recipe calls for separated egg whites and egg yolks, whip the egg whites, and then fold the egg whites into the batter. It seems fussy, why not just add the eggs in all at once? By whipping the egg whites and folding into the batter it gives the cake a light, spongy texture. This is the reason why I chose this recipe for my cake. Worth the extra step, I promise you! Pour it all into a nice cake/casserole pan and BOOM, done.

swiss buttercream on a whisk attachment — Swiss buttercream texture

Unicorn Frosting Dreams

You could easily make a frosting, spread it on top and call it done but I wanted to try the beautiful piped frosting that takes this simple sheet cake next level. Swiss Buttercream uses egg whites heated with sugar and then whipped with butter. It is light, smooth and not overly sweet. King Arthur Flour's recipe for Swiss Buttercream is simple and makes just the right amount.

I used the Wilton Gel Food Colors to color the frosting because I was trying to get bright colors. I was little horrified at how much is required to get the colors to pop and I still felt my colors weren't as bright as what I envisioned. I may try natural colorings next time.

I'm going to be honest here, this was a lot more work than I anticipated. Making the frosting, coloring the frosting, putting them into individual piping bags, making the swirled rainbow piping bag, and frosting the whole sheet cake took much longer than I thought. But I am super stoked at the results! I couldn't tell you which piping tips I used because I have a cheap set of tips that are not numbered, unlike the pro Wilton ones. *sigh* Maybe one day I'll invest in a nicer Wilton piping set.

The good news here is that there's really no way to go wrong here. I swirled stuff, made some stars, roses, swirls, filled in the gaps and voila! I realize that I'm making this sound easy, and it wasn't, but all it took was some patience and determination. YOU CAN DO IT!