Japanese sponge cake (castella)

Castella is one of the most interesting sponge cakes you’ll ever make. With its beginnings coming from Portuguese traders but with centuries of adaptation in Japan, and made from bread flour leavened only with egg, this half-baked, half-steamed cake is as unlikely in its method as it is in its origins.

• serves

  20

• prep

  1 hour

• cook

  1:10 hour

• difficulty

  Ace

Ingredients

• 5 eggs, plus 2 egg yolks
• 180 g caster sugar
• 70 g honey
• 2 tbsp mirin
• 40 ml boiling water
• 180 g bread flour
• 30 g unsalted butter, melted
• 60 g raw sugar crystals

Resting time overnight

You will need to begin this recipe 1 day ahead.

Instructions

First, prepare the wooden boxes for baking. For the lower box, wrap each of the four sides in a layer of copy paper, securing the paper to itself with glue on the external side of the box. Next, line each side with baking paper, overlapping the base by about one-third of the box’s width. Line the base with baking paper the size of the internal dimensions of the box. P­lace the whole box on another base made of three sheets of copy paper wrapped in baking paper. Wrap the sides of the upper box in a single layer of copy paper.

Preheat the oven to 210°C fan forced.

Lightly beat the eggs, egg yolks and caster sugar in a metal bowl set over a water bath, until the egg mixture reaches 40°C on a thermometer. (You can do this directly in the bowl of a stand mixer.)

Combine the honey, mirin and boiling water until smooth.

In a stand mixer, whisk the egg mixture for 7-8 minutes or until it is light, fluffy and holds a ribbon when whisk is lifted out of the mixture. Add the honey mixture and beat for a further 1 minute.

Sift in the flour and whisk for 1 minute, then add the butter and gently stir through without beating.

Scatter the sugar crystals over the base of the lower box and pour the cake batter through a fine sieve over the crystals.

Run a spatula through the mixture three times to remove any air bubbles, and smooth the surface of the batter with a pastry scraper.

Bake the castella on the centre shelf of the oven for 10-15 minutes or until the top is a rich golden brown. Carefully add the upper box and lid, and reduce the temperature to 160°C fan. Bake for 1 hour.

Remove from the oven and remove the upper box. Turn the lower box out onto a cutting board lined with plastic wrap. When the cake is cool to the touch, remove the lower box and wrap the cake securely in plastic wrap and keep wrapped overnight.

Unwrap the castella, slice and serve.

Note

• If you don’t have special castella boxes, they can be improvised using two square cake tins of the same size with removable bases.

Cook's Notes

Oven temperatures are for conventional; if using fan-forced (convection), reduce the temperature by 20˚C. | We use Australian tablespoons and cups: 1 teaspoon equals 5 ml; 1 tablespoon equals 20 ml; 1 cup equals 250 ml. | All herbs are fresh (unless specified) and cups are lightly packed. | All vegetables are medium size and peeled, unless specified. | All eggs are 55-60 g, unless specified.