Giant castella (jiggly sponge cake)

Nest the tall cake pan in a larger roasting tray and pour in water to test how much the inner pan displaces; the water need not reach all the way up the sides.

Remove the inner pan and put the tray of water into the oven to heat with it, to 325F (160C), convection fan off.

Separate 20 eggs, whites into one huge bowl and yolks into another, keeping every trace of yolk out of the whites.

To the yolks add 250 g vegetable oil, 250 g milk, 250 g cake flour, 25 g cornstarch, a glug of vanilla and a heaped teaspoon of salt.

Weigh 270 g sugar into a separate bowl.

Add a little cream of tartar to the whites and beat with an electric mixer about 5 minutes until fluffy.

Beat in the sugar gradually, about half at a time, until the meringue is firmer and glossy, to medium peaks.

Beat the yolk mixture until smooth.

Stir the meringue into the yolk mixture in a couple of installments until no yellow streaks remain.

Line the pan with parchment, two strips for the sides and one long one down the middle with excess to use as a sling.

Pour in the batter and drop the pan into the water bath in the oven.

Bake about an hour and a half, then test with a skewer; adjust the heat if the top browns too fast or too slow.

Bake about 10 minutes more, until the skewer comes out clean.

Lift the cake out using the parchment as a sling and peel off the paper.

Slice with the longest knife available; flavour improves as the cake cools.