This article is part of Spring Bake, a collection of brand-new recipes and ideas that will keep you in cake, buns, and cookies until summer.
March is the month of birthdays in my life. It’s my own birthday month, my partner’s birthday month, and the birthday month for about 25 of our friends. Historically, I’ve been inclined to celebrate all of these birthdays properly: with a big, boisterous layer cake.
But last year, when The Great Birthday Month entered its Pandemic Edition, I couldn’t bring myself to do it. Why make a full 9-inch layer cake if I can’t throw the kind of big party that demands it? For Pandemic Edition: Year Two, however, I’m baking my way toward a return to normalcy. I'm baking layer cakes again. They’re just going to be 6 inches.
Nine-inch cakes make sense at bakeries and events: You get 12 wedge slices from a 9-inch cake, or 30 1x2-inch wedding slices. But that’s an oppressive amount of cake for a modest gathering of newly vaccinated friends—and many days of cake-eating homework for an isolated household of two. For now, a 6-inch cake will do quite nicely, thank you.
While it packs the same festive punch as a 9-inch cake, a 6-inch layer cake just feels more casual than its full-size counterpart. Show up to someone’s house tomorrow and surprise them with a full-size layer cake that can feed 12? You look like a crazy person. But it’s a real power move to arrive with a tidy little 6-inch cake under your arm. It’s impressive but approachable—the Baby Yoda of cakes.
Here’s the only problem with 6-inch layer cakes: There aren’t many recipes written to accommodate a 6-inch cake pan. I just wrote a 6-inch recipe for my newsletter: a banana pudding cake with Nilla wafer buttercream for my partner’s birthday. But if you’re working with a layer cake recipe from the Before Times (or any recipe for an 8- or 9-inch cake), converting it to a 6-inch cake is an easy fix. It just takes a little bit of math. Don’t worry, it’s the fun kind of math—cake math.
TLDR: Wanna skip the math?
So you need a 6-inch cake ready in the next two hours and you don’t have time for cake math? Fine. Grab a layer cake recipe that calls for 8- or 9-inch round pans and multiply each of the batter ingredients by 57% (if starting from an 8-inch recipe) or 45% (if starting from a 9-incher). Make the cake using those smaller quantities of each ingredient and skip below to my instructions about baking times.
Need more details? Love to learn? Keep reading.
Cake math, step 1: calculate the area
To convert a recipe for any big cake into a recipe for 6-inch pans, start by determining the area of the larger cake pans. For square and rectangular pans, this is easy to do—just multiply the length and the height (a 9 x 9 pan = 81 square inches). Of course, layer cake recipes rarely use square or rectangular pans, which means you’ll probably have to calculate the area of a circular pan.
The area of a round cake pan can be calculated by multiplying π (3.14 is good enough) by the radius of the pan, and then squaring it (in other words, multiplying it by itself). Remember, the radius is half the diameter. So for a 6-inch round cake pan, π x 3 x 3 = 28.26 in2 (which, for sanity’s sake, you would round up to 29 in2).
Want to skip the pi part and get right to cake? Here’s a cheat sheet for the most common round cake pan sizes:
Area of a 6-inch round pan: 29 in2
Area of an 8-inch round pan: 51 in2
Area of a 9-inch round pan: 64 in2
Area of a 10-inch round pan: 79 in2
Cake math, step 2: convert the measurements
Now that we have the area of the pans, it’s easiest to work in percentages. Divide the smaller pan area by the larger pan area to calculate your percentage. For example: 29 in2 (the area of 6-inch pan) divided by 51 square inches (the area of an 8-inch pan) = 57%. So a 6-inch pan is 57% of an 8-inch pan’s area.
Next, we use these percentages to convert the ingredient measurements. Multiply the original larger recipe measurement by the percentage to find the measurement of each ingredient for your smaller cake. Write down your results—don’t do this in your head as you go!
It’s best to do your conversions in grams. So, if an 8-inch cake requires 500 grams of flour, multiply that by .57 or 57% to find the measurement for the 6-inch recipe. 500 x .57 = 285 grams of flour. (If you need to convert a recipe from volume to grams, King Arthur Flour has an excellent ingredient weight chart.)
When you’re converting measurements, you’ll need to do some slight approximations, but don’t get too nervous about that. Round to the closest gram, up or down, except in the case of leaveners—I always round up on the leavener, because I’d rather have a little extra lift in the cake than not enough. You can just round to the nearest egg, too. If you want to get super-technical on the eggs, whisk an egg until homogenous and weigh out what you need. Save the rest for an egg wash (or a little treat for your dog). When you’re dealing in measurements as small as a tenth of a gram, again, don’t stress. Whichever way you round, your cake will be totally fine!
As an example, let’s convert Shirley O. Corriher’s Deep, Dark Chocolate Cake from a 9-inch cake to a 6-inch cake.
Or let’s convert this Banana-Chocolate Chip Cake from Janet McCracken and Alison Roman from an 8-inch to a 6-inch cake.
Cake math, step 3: bake—but watch the time
Once you’ve scaled down your ingredients, you can make the cake exactly to the recipe’s specifications—except when it comes to baking time. For that, you’ll need to play it by ear. Keep the listed baking temp from the recipe the same, but don’t wander far from the kitchen. Start conservatively. If a recipe calls for a 25-minute bake time for a 9-inch cake, start with 10 minutes for a 6-inch cake, rotate the cake in the oven (you’re always rotating your cakes, right?), then give it another five minutes. Or, if you think it’s close, give it only another three minutes. Doneness is measured either when a cake tester comes out clean, or when the surface has a light spring when touched. Keep testing the cake until it’s done.
Tools of the small cake trade
The tools you need to bake and decorate a 6-inch cake are exactly the same as those you need for standard 8- or 9-inch cakes. Well, almost. There are a few things you need, and a few more that aren’t technically necessary but are really nice to have.
6x3-inch Cake Pans: The main character of today’s story. A 6x2-inch pan will work, of course, but I like the 3-inch tall pans. They give you a little more wiggle room if your conversion doesn’t quite fit.
Ateco Professional Offset Spatulas: For everyday baking you’ll want a large and a small offset spatula. But for 6-inch cakes specifically, there’s a middle size that’s great. (Side note: I like a sturdier, stiff offset rather than a flimsy one with too much give. These are nice and beefy.)
6-inch Cardboard Cake Rounds: This is the base to build your cake on. You can, of course, cut your own out of scrap cardboard, but these are inexpensive and make your cake feel 400% more professional.
Finally, a note on frosting
You may have noticed that I only covered scaling down cake in this article, not the frosting. That was by design. Make the amount of frosting the 8 or 9-inch cake calls for, and you’ll have plenty to use for piping decoration. And if you have extra? Freeze it and use it for an impromptu single layer snack cake at a later date.
So go forth, cut down your cakes to size! But always make the full batch of frosting.
Originally Appeared on Epicurious