Rainbow Cat-icorn Cake

Stringbean turned 9 on Thursday! And yesterday, we had a birthday party for her.

Our communal obsession with cakes has taken many forms. For Stringbean, she has been working on her birthday cake design for months. We had to negotiate a bit to fit her expectations within my abilities, but in the end, we achieved something awesome. It was a crazy journey, but we had lots of fun, and I learned so much!

Meet the rainbow cat-icorn cake. Two tiers, four layers each, with dyed vanilla cake and buttercream frosting.

I’ll start with the inside.

For the actual unicorn part, we followed a lot of this video by Sugar Geek Show. One of the things we loved about that video was the rainbow-swirl cake batter made in a really fun and easy way. It turned out so fun. (The actual cake recipe we used was, again, the YBD Vegan Vanilla recipe. These YBD vegan oil cake recipes are so easy that I can’t bring myself to try any others yet.)

Since we had the four colours anyway, and we were doing two tiers, I made the 6-inch tier with solid cake colors. That ticked an item off my bucket list. These cakes with rainbow innards make me so happy.

So that much was pretty easy.

Then we did a brand-new first: we made and used fondant!

I had bought a few boxes of fondant from Superstore last summer, but I wanted to use them to make Sugar Geek’s easy marshmallow fondant. Supposedly it tastes a lot better, is easier to work with, and will stretch the expensive fondant by means of cheap marshmallows.

It worked a treat! We made a big batch, most of which will be saved for Dooner’s cake, and used a small amount to make the unicorn horn and the cat face.

I’m not sure when the unicorn became a cat. I think Stringbean just wanted to make more face pieces and paint them. The eyebrow shapes weren’t enough.

That was another first: hydrating powders to make edible paint. I don’t have alcohol in the house, let alone vodka or everclear, so I hydrated them with “ReaLemon” lemon-related juice. It worked great with the black Wilton’s powdered food coloring. Not so much with the silver shimmer dust. I haven’t had the greatest luck with that stuff. Dry, it doesn’t do much; wet… it’s clearly not meant to be used wet.

Stringbean made the face and ears herself; I did the eyes. She had loads of fun painting them.

Then I started making buttercream.

Oh, the buttercream.

My biggest lessons from this and my other most recent cake is all the things that can go wrong with Swiss merengue buttercream.

  1. PAY ATTENTION when pasteurizing egg whites – do not let the water boil, or fail to whisk enough, or you WILL cook them.
    • pro tip: a gun-type thermometer with a “surface” function is definitely good enough for tracking temps on pasteurizing egg whites, and saves some effort.
    • I can definitely see why the pros just buy a box of pasteurized egg whites. That would make this a very easy frosting.
    • Note to self: learn some different frostings.
  2. There is a reason that it’s kinda hard to find a lemon-flavored swiss merengue buttercream. They’re kinda harder to get right. At least, I had a hard time with them.
  3. Read the recipe, every time. Once you whip your merengue with half the amount of sugar, and wreck the merengue by adding the butter (too much at a time and too hard to boot), there’s no coming back from that.
    • Oh, also, make sure your butter is actually soft, and don’t add it too fast.
    • You can add as much powdered sugar as you want; it’s still not going to make your butter-soup into something pipeable.
    • note to self: find a use for 10 cups of lemon-flavored butter-glaze.
  4. Do NOT leave Swiss merengue buttercream out on the counter overnight. Even if you live in a cold place. Yes, I know you can leave a fully decorated cake out for a couple of days, but not the bagged frosting. It will separate into a grainy-looking disgusting mess. You have to go to the trouble of refrigerating it, then pulling it out ahead of time to soften.

I made four batches in all, and I do not feel comfy about the amount of scrambled egg yolks we’ve consumed as a result. (But I am extremely thankful for my new stand mixer.) Another note to self: find something to do with egg yolks.

I managed to make enough lemon Swiss merengue for the bottom tier. My next attempts failed so miserably that I gave up and made my old standby SMB from Craftsy. I covered the top cake, colored the rest, and left it overnight to become a cautionary tale. One more batch later, and I was finally ready to decorate.

I did the rainbows first. I have so much practice to do in piping! Just making a straight stripe with the star tip did NOT work, so I switched to sort of wavy shells; it works in a messy sort of way. Stringbean added the marshmallow clouds.

Then I put the four colors into a “bullet” (another new technique for me, from the SGS Unicorn Cake episode) and made the hair. This was by far my favorite part, both to do, and to see the final effect! The pink somehow receded in the bullet until there wasn’t much showing, so I used the pink to make little filler accent stars. Some blue purls to accent, and voila! Super-chic Cat-icorn hairdo.

These last two cakes have taught me the important of accents. You can have the most elaborate design in the world, but nothing brings even a bland design to life like little pops of something-something. With a colorful, fun design, they dazzle!

The final touch was a little white buttercream to hide the seam between the two tiers, giving our cat-icorn a little pearl necklace. These were followed by the graduated white dots (of which apparently one fell off?) which is a great trick I’ve seen JJR use a lot, but which isn’t too hard for my piping skill level.

Stringbean was super-proud. I confess, I am too – I worked hard to make her dream cake come true. She loved showing the cake off to her friends, blowing out her nine candles, and sharing it with them.

As usual, she ran a great party – she designed and handed out the invitations, planned the dice games, decided on the food, and more or less kept things humming. It was a small crowd because we committed to sticking with the current covid restrictions on our community, but four kids plus our three was plenty!

Even Sisko had fun.

We also had the boon of my mom helping out. Just having another reliable, calm adult would be boon enough, but she’s also… well, my mom. It has been so, so great having her here.

MiniMighty and Dooner have been good birthday helpers. It’s not easy when your big sister is the center of attention for several days, but they did great considering, and Stringbean is generally pretty good at bringing her sisters along for the fun. Even when there are new LEGO Friends sets involved.

Birthday season is off to a great start in the Osborn household. It’s been a complicated week, but we got a buttery-sweet happy ending. Happy birthday to my big girl.

5 thoughts on “Rainbow Cat-icorn Cake

  1. That cake is EVERYTHING!!! I need a caticorn in my life! Happy Birthday, N! I can’t believe you are NINE! How did that happen?!?!?


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