Kasutera: A Fine Yellow Crumb and a Crunch of Sugar Underneath
A fine, even yellow crumb from well-whipped eggs, a gently browned top, and a thin layer of coarse sugar baked onto the bottom. Everything in this recipe serves those three things.
Cut a slice of castella and the first thing you notice is the crumb: small, close bubbles and a yellow color that comes from whole eggs. Turn the slice over and there is the second thing, a layer of coarse sugar crystals stuck to the base, which gives a little crunch against the soft cake. In Japanese the cake is called kasutera (カステラ).
The version in this article is a home recipe published by Japan's Ministry of Agriculture, Forestry and Fisheries (MAFF) in a feature on regional sweets that celebrate sugar. It uses just six ingredients, an ordinary hand mixer and a 24 × 13 × 4 cm pan, and bakes at 170°C for about 30 minutes. It is a home version that spreads coarse sugar on the bottom of the pan; it is not presented as the definitive formula of Nagasaki's castella makers, who use their own ingredients and methods. It is also a different cake from Taiwanese castella, which is a separate dish with its own search results and recipes.
This recipe has not been kitchen-tested by Sekai Gohan.
Because the recipe has so few ingredients, the result depends on reading the batter at each stage: how thick the whipped eggs are, how gently the flour goes in, and whether the skewer comes out clean. Those checks are what the steps below are built around.
Ingredients: Six Items for One 24 × 13 × 4 cm Pan
This makes one pan measuring 24 cm long, 13 cm wide and 4 cm deep.
Do not give this cake to babies under one year old. Honey and foods containing honey must not be given to infants under one, even after normal baking. The cake also contains egg, wheat and milk.
Equipment
- Rectangular cake pan, 24 × 13 × 4 cm
- Oven
- Parchment paper (oven sheet) to line the pan
- Mixing bowl
- Hand mixer
- Sieve for the flour
- Rubber spatula
- Bamboo skewer
Choosing and Swapping: What to Keep the Same
Cake flour. Use cake flour here.
Coarse sugar is for the bottom only. Chūzaratō, often simply called zarame, is a large-crystal sugar. In this recipe it is spread over the paper in the pan, not stirred into the batter. If you leave it out you get a castella without the crunchy base, which is a different finish from the one shown here.
Keep the honey, milk and sugar as listed. Use the honey and milk in the listed amounts. Anyone who cannot have honey, egg, wheat or milk should choose a different recipe rather than adapt this one.
Eggs. Use 2 whole eggs.
Pan size matters. The baking temperature and time belong to a 24 × 13 × 4 cm pan. There is no way to convert them reliably for a pan of a different size or depth, so look for a pan as close to these dimensions as you can.
Method: Whip, Add, Fold, Bake, Test
Whip until the batter holds a trail, fold the flour without stirring hard, and decide when the cake is done with a skewer, not only by the clock.
Serving: Slice Once It Has Cooled
Slice the cake once it has cooled. Each slice should show the yellow crumb, the browned top and the line of coarse sugar along the bottom. The recipe makes one pan and does not set a number of slices, so cut it to the size you like.
Troubleshooting: Reading the Batter and the Skewer
| What you see | What to check | What to do |
|---|---|---|
| The whipped eggs do not leave a trail | Whether the batter has turned pale and thick | Keep whipping until the batter falling from the beaters leaves a trail on the surface |
| Streaks of flour remain | Whether you have folded through to the bottom of the bowl | Fold lightly with the spatula; do not switch to stirring hard or kneading |
| The batter has become loose and runny after adding the flour | How hard it was mixed | Next time, fold with cutting strokes without kneading |
| Batter clings to the skewer after about 30 minutes | Ovens differ | Bake longer and test again with the skewer; do not decide by time alone |
| The coarse sugar is scattered through the cake | Whether it was mixed into the batter | Spread it on the paper in the pan before pouring, and leave it there |
| Your pan is a different size | The dimensions | The baking time cannot be converted for other pans; use a 24 × 13 × 4 cm pan or one close to it, and rely on the skewer test |
Variations: Related Styles That Are Different Cakes
These are not substitutions within this recipe; each is a different formula or method.
- Without the coarse sugar: the same batter baked without the sugar layer gives a cake with no crunchy base, a different finish from this one.
- Bread-flour home versions: JA Zen-Noh Tamago's "local recipe" for Nagasaki-style castella uses bread flour, kibi (cane) sugar and salad oil, whips the eggs over hot water and adds the flour in three parts. It is a separate recipe with its own proportions, not a variant of the amounts here.
- Makers' castella with starch syrup: the Nagasaki maker Fukujuya Honpo lists starch syrup (mizuame) among its basic ingredients. No home amount is given, so it is not added here.
- Gosanyaki and Taiwanese castella: both are separate styles and are not covered by this recipe.
Castella in Japan: Home Recipe and Nagasaki Makers
MAFF published this recipe in a feature called "Furusato no aji jiman" (hometown flavors to be proud of), which focused on regional sweets that celebrate sugar. It is written for home kitchens: a small rectangular pan, a hand mixer and a single bake.
JA Zen-Noh Tamago, notes that castella in Nagasaki is often made with coarse sugar on the bottom. Fukujuya Honpo, a Nagasaki castella maker, lists eggs, white sugar (jōhakutō), coarse sugar, wheat flour, starch syrup and honey as its basic ingredients; it describes whipping the eggs, choosing the flour and the texture of the coarse sugar as matters of technique, and says it rests its castella overnight after baking to let the crumb settle. Izumiya, which runs a castella-making experience in Nagasaki, shows a process of mixing starch syrup, sugar and eggs, whipping them over hot water, pouring into a pan lined with coarse sugar, breaking up the bubbles in the batter (awakiri), baking and unmoulding.
Those are the makers' own products and processes. The home recipe in this article does not use a water bath, starch syrup or an overnight rest, and it does not claim to reproduce a Nagasaki maker's cake. Stories about where castella and its name came from are told in several places, but the sources gathered here do not confirm them, so this article leaves them aside.
For more dishes from the same country, see Japan.
Frequently Asked Questions
Can I give this castella to a baby?
Not to a baby under one year old. Japan's Ministry of Health, Labour and Welfare advises that honey and foods containing honey must not be given to infants under one. Botulinum spores are not killed by ordinary heating or cooking, so this applies to baked foods like this cake too.
Why is the pan lined and sugared in step 1?
In the MAFF recipe, the pan is lined and the coarse sugar spread after the batter is made. Here that preparation is moved to the start so the whipped batter does not have to wait while you line the pan. The amounts and the position of the sugar are the same either way.
Does it matter whether the honey or the milk goes in first?
The MAFF recipe adds the milk and honey at the same stage and does not fix an order between them. The photo for step 3 shows the honey being poured in after the milk; that is simply the order used for the photo.
Do I need a water bath or an overnight rest?
Not for this recipe. Whipping the eggs over hot water appears in JA Zen-Noh Tamago's recipe and in Izumiya's castella-making experience, and resting the cake overnight is part of Fukujuya Honpo's method. Those steps belong to those methods; the MAFF home recipe whips the eggs without a water bath and simply cools the cake before unmoulding and slicing.
Is this the same as Nagasaki castella?
It is a home version with coarse sugar on the bottom, which JA Zen-Noh Tamago describes as common in Nagasaki castella. But Nagasaki makers use their own ingredients, such as starch syrup, and their own processes, so this recipe is not presented as their formula.
How many servings does it make?
One 24 × 13 × 4 cm pan. The MAFF recipe does not state a number of servings or slices.
Sources
- Ministry of Agriculture, Forestry and Fisheries (MAFF), "Furusato no aji jiman: Satō o tanoshimu kyōdo no kashi — Kasutera" (Hometown flavors: regional sweets that celebrate sugar — Castella). The recipe used in this article: the 24 × 13 × 4 cm pan, the six ingredients and amounts, the order of whipping, adding the honey and milk, folding in the flour in two additions and spreading coarse sugar on the bottom, baking at 170°C for about 30 minutes, and the skewer test. https://www.maff.go.jp/j/pr/aff/2111/spe1_04.html
- JA Zen-Noh Tamago, "Gotōchi recipe! Nagasaki-ken kasutera" (Local recipe: Nagasaki castella). The note that coarse sugar is often used in Nagasaki castella, and a separate home recipe with bread flour, kibi sugar, salad oil, a hot-water bath and flour in three additions, used for comparison only. https://www.jz-tamago.co.jp/customer/atoz/recipe/a2z00016792/
- Fukujuya Honpo, "Kodawari" (Our approach). A Nagasaki castella maker's basic ingredients, its explanation of egg whipping, flour choice and coarse sugar, and its overnight rest after baking. https://fukujuya-honpo.co.jp/kodawari.html
- Izumiya, "Nagasaki kasutera-zukuri taiken" (Nagasaki castella-making experience). The steps of the facility's castella-making experience, used as a process comparison only. https://www.n-izumiya.com/castella-taiken/
- Ministry of Health, Labour and Welfare, "Hachimitsu o ataeru no wa issai o sugite kara" (Give honey only after age one). The caution that honey and honey-containing foods must not be given to infants under one, because botulinum spores are not killed by ordinary heating. https://www.mhlw.go.jp/stf/seisakunitsuite/bunya/0000161461.html
