So, my friend Liz loves rainbow chip cake.
Liz is one of my best friends, and the list of things I wouldn’t do for her is short. I recommended her for a job at my office, which she subsequently got hired for and of course excels at. I give her advice when she asks for it, and try very hard to shut up when it’s not wanted. I’m always willing to lend her money if needed, which is not something I do lightly. But one thing I cannot do for her is make a Betty Crocker box mix cake. Even for her birthday.
I just can’t.
This is not the first time I attempted to make her box-mix fantasy a from-scratch reality. A few years ago, I made her a Funfetti cake. Because she had told me her favorite cake was Funfetti. She kept going on and on about the “little balls” for the frosting. “That’s the best part!” Having always been more of a chocolate girl myself, I don’t have any childhood memories of Funfetti cake. I knew Funfetti was sprinkles, so I picked up a bottle of those jumbo rainbow nonpareils to sprinkle on top. Funfetti = sprinkles. “Little balls” = jumbo nonpareils, right?
So, I whipped up a basic white cake with rainbow jimmies mixed into the batter, and frosted it with a basic buttercream. I piped “friends love Liz” on the top in green icing (we had been re-watching Arrested Development around this time — “Take a look at banner, Michael!”). And topped the whole dang thing with those jumbo nonpareils. I even made a homemade cake topper re-enacting the time her cat got his head stuck in a jar! (It’s a long story, but the high point is my mister rolling over and groggily telling me to “go be a hero” at two o’clock in the morning when this occurred.)
Anyway, this cake was perfect! Just perfect! Except for two things: 1) Liz had said her favorite cake was Funfetti, which is the Pillsbury white cake with sprinkles. In fact, her favorite cake is Rainbow Chip, the Betty Crocker white cake with colored, soft candy chips mixed into both the batter and frosting. Those candy chips, I now know, are the “little balls” she kept going on about. 2) Before Liz had a chance to actually eat any, someone started a cake fight. Yeah. I was not enthused to scrape cake and frosting off of all the surfaces of my kitchen. But the silver lining was that Liz didn’t get to taste my completely wrong cake and demand that I never defile her precious “Funfetti” (read: Rainbow Chip) box mix with a homemade version again.
For my second chance, I was prepared. I was inspired by this post — homemade rainbow chips are clearly the only way this cake can work. But I can’t get behind seized chocolate. I knew Liz would be a stickler for texture. The chips in the frosting are supposed to be velvety soft and easy to bite into, a mouthfeel that regular white chocolate cannot provide. Enter modeling chocolate. A bit of work? Yes. Exactly what this recipe needs? Also yes.
If you have any trouble with the modeling chocolate portion, you should really just hop on over to Hungry Happenings. Beth has great step-by-step photos and troubleshooting tips. I’ll admit, on my first attempt at this, I had… a bit of trouble. It’s been pretty hot here lately, and my mister is very… frugal… so he doesn’t like to crank the A/C. So it was very hot in the kitchen when I attempted this, and I had the problem of the oil separating out of the cocoa butter. I kneaded and kneaded but it was just getting worse and worse, because it was So. Damn. Hot. I decided it was a lost cause, threw it in a container in the fridge to deal with later, and consoled myself with the fact that at least my hands were incredibly moisturized as a result of my failure. After a night in the fridge, my chocolatesque mess had hardened into a layer of solid cocoa butter on top of a layer of the rest of the stuff. I decided to see if it could be saved. I broke the cocoa butter into chunks and massaged it so it melted slowly, all the while kneading it back into the dough. It took a long time, but it worked eventually. The resulting modeling chocolate would probably not have been ideal for most modeling chocolate purposes, but for the rainbow chips it was workable. If you want to avoid the potential nightmare of making your own modeling chocolate, you can also buy it online. Then you just have to deal with the tediousness of making the chips from it!
In case you hadn’t figured this out already, this cake is a labor of love. Have a good podcast to listen to or something to watch on Netflix while you’re prepping all those rainbow chips, is all I’m saying.
Initially, I planned to use the homemade rainbow chips in both the frosting and the cake. I coated the rainbow chips in flour before mixing them into the batter to prevent them from sinking to the bottom… this was a failure. My first attempt ended up as more of a white cake with a kaleidoscope bottom; not so much a rainbow chip cake. So, given that they just melt into indistinguishable color splotches in the cake anyway, I decided that using plain old rainbow jimmies would be fine as long as the frosting was right. Those little balls.
Anyway, while it may be homemade, there’s nothing nutritionally defensible about this cake. It’s filled with super bleached cake flour and corn syrup. But at least it’s not a box mix, right? Right??
All the Colors of the Rainbow (Chip) Cake
Inspired by Homemade Rainbow Chip Cake by Not Without Salt
Various parts and portions adapted from or instructed by King Arthur’s Elegant White Cake by Cookie Madness, Modeling Chocolate by Joy of Baking, and Chocolate Basics by Hungry Happenings
16 ounces white chocolate
1/3 cup light corn syrup
gel food coloring
1/2 cup butter (1 stick), softened
1/2 cup vegetable shortening
1 3/4 cups sugar
1 tablespoon baking powder
3/4 teaspoon salt
2 teaspoons vanilla extract
3/4 teaspoon almond extract
5 large egg whites, at room temperature
2 3/4 cups cake flour
1 cup whole milk, at room temperature heaping
1/4 cup jimmies, rainbow or in any color(s) you want
1 cup butter (2 sticks), softened
8 ounces (1 package) cream cheese, softened
4 cups sifted powdered sugar
1 1/2 teaspoons vanilla extract
heaping 3/4 cup rainbow chips
Melt your white chocolate in a double boiler (or if you’re classy like me, a metal bowl over a saucepan). I generally put the chocolate in the bowl, the bowl on top of the pot and keep the stove on until the chocolate just starts to melt. Then cut the flame and stir the chocolate around. Once it’s almost melted with just a few bits, move the bowl over to the counter (away from the pot) and continue to stir, letting the residual heat melt the last bit of the chocolate. Pop your thermometer in there, and continue stirring until it cools to around 91 degrees. If you haven’t heated the heck out of it in the first place, it shouldn’t take too long. Really. Don’t keep it on the double boiler until it’s molten lava. Let residual heat do the work for you. If you do not have a thermometer, Beth of Hungry Happenings recommends putting a smidge on your lip — it should feel cool, unless you are some kind of weird medical marvel or a snake/lizard.
Add corn syrup, and stir (quickly!) to combine. It will thicken up very fast. Scrape the mixture onto a counter top or cutting board. Knead until smooth.
So you’ve got your giant ball of modeling chocolate. Split it into as many equal portions as colors you want to use. The original rainbow chip cake has pastel pink, blue, yellow, and green, so stick with those if you’re a traditionalist. You could also do just a few contrasting or coordinating colors — wedding colors for a bridal shower, sport team or school colors, or just the favorite colors of whomever you’re making it for. But I wanted to go all out and use all the colors of the rainbow. You ask me to make you a rainbow chip cake? I will make you a rainbow chip cake.
Using a fresh toothpick each time, drag some gel color onto your first ball of chocolate. I’m not going to give exact measurements because it will depend on your gel and your preference, but start with less than you think you need! Knead until all the color is incorporated and it’s not streaky, and add more gel as needed until you are happy with what you’ve got. Roll it into a ball, flatten into a disc, and wrap tightly in plastic wrap. Repeat for each color.
You can make this well ahead of time (a couple of months, even), and just throw the plastic wrapped discs into a zip top baggie in the fridge. You should plan on making your chips at least a week or so before your bake time, because it will probably take longer than you think. My original plan was to roll the modeling chocolate into long, skinny snakes, and chop them up to get cylindrical bits. However, the combination of my questionable modeling chocolate and my superheated house, it was just not cooperating with that. You might try this, but if it doesn’t work out, you’ll have to do like I did: Watch a few episodes of The X-Files and roll little balls from your modeling chocolate. Mine were about the size of brown lentils, maybe a tad bigger. I put them on a cookie sheet as I rolled them, and once one was filled I put it in the freezer. Then, once I had filled another, I took the original one from the freezer, used a spatula to pry them all up, and put them in a storage container to return to the freezer. Repeat until you’ve used up your chocolate, and store the completed rainbow chips in your freezer until ready for use.
Oh my god, this recipe is already so long and we haven’t even gotten to the cake. I will try to keep the rest of this brief.
Prep two 8- or 9-inch round cake pans: spray or butter the bottom and sides, throw a parchment paper circle on the bottom, then spray or butter the parchment. You are all using Alton Brown’s fabulous tip for cutting parchment circles, right?
Go ahead and preheat your oven to 350, too.
In your mixer with the whisk attachment, cream butter, shortening, sugar, baking powder, salt, and extracts on medium speed for about 5 minutes, until light in color. Add egg whites one at a time, allowing each to be fully integrated before adding the next. Add one third of the flour, then stir on low to combine. Same deal with half the milk. Scrape down the sides as necessary. Repeat: flour, milk. Then top it all off with the last of the flour.
You don’t want to over mix — that will overdevelop the gluten which will give you a tough cake. It’s better to err on the side of caution and turn it off while there are still some lumps and streaks. They’ll get mixed in while you fold in the jimmies. Which you should do now.
Pour batter into pans, pop in the oven, and bake for 25-30 minutes, until a toothpick comes out clean. Once you’re getting close, check that sucker often. White cake can dry out so easily, so you’ve got to get it out when it’s just barely done. Let cool for 10 minutes in the pans on a wire rack, then remove from the pans and let cool completely.
Frosting! This is pretty similar to the frosting I use on the Carrot Cake for Someone Special, only with the cream cheese dialed down — it’s not a cream cheese frosting, it’s a buttercream frosting with a tang. So, follow the same procedure there: mix butter and cream cheese with whisk attachment until fully combined, add the sifted powdered sugar in increments to prevent dusting your entire kitchen in it, add vanilla extract, whip until fluffy. I didn’t do this, but I’d highly recommend setting aside some of the plain frosting to do a crumb coat with.
But then! Those little balls. Gently fold in your painstakingly created rainbow chips. I did this before a five hour drive to beach, with the frosting in a cooler. Then the cake ended up being stored overnight in the fridge after being frosted, because everyone got too full/inebriated to eat it. The colors from the chips didn’t bleed. I don’t know how long it would be before they started to. I’m just giving you the information I have.
Now, you know what to do! Plop the first layer down, frost the top almost out to the edge, plop the second layer, and frost the top and sides. (Like I said, a crumb coat with the plain frosting is recommended.) Be sure to put strips of parchment paper underneath your cake while you’re frosting — when you’re done you just pull them away and your plate/pedestal is pristine! If you have any leftover modeling chocolate, you don’t have to let it go to waste. Modeling chocolate is also known as chocolate clay, which is quite the accurate name for it. You can sculpt or cut out anything that tickles your fancy and throw it on top of the cake as an edible decoration.