While the cream cheese mix warms, weigh the flour, cornflour, milk
powder and 60 g (2 oz) of the sugar into a bowl and set aside with a sieve.

Because this is going in to make a paste, there’s no need to sift multiple
times to blend the cornflour and flour.

When the cream cheese base is quite warm (70°C/158°F) and
smooth, remove the bowl from the saucepan, sift the dry ingredients
over and hand whisk well to make a smooth paste. Hand whisk in the
yolks and yuzu and scrape the sides down.

Put the egg white, remaining sugar and cream of tartar in the bowl of
an electric stand mixer. Using the whisk attachment, whip on speed 8
(under high) for 1 minute, then check the meringue. Super important:

make sure your meringue only reaches soft peak. It should only just

hold a droopy peak on your fingertip, and a folded over peak when
the whisk is pulled out.

Too stiff a meringue will cause cracks in the cake.

Gently fold one-third of the meringue into the cream cheese base
until it is almost fully incorporated. Then gently fold in the remaining
meringue until the mix is perfectly cohesive with no distinct white
or creamy yellow batter streaks remaining. Do the final folding with
a flexible plastic spatula. The batter should be loosey moussey
and runny, not scoopable AT ALL. Tenderly scrape the mix into the
prepared cake tin and give the mix a swizzle with a skewer or small
knife to even out any large air pockets.

Pour a shallow amount – up to the first knuckle on your finger – of hot
water from the double boiler into the ceramic tray. Place the tray in the
oven and bake for 20 minutes, until the top has a honey-gold crust.

Fine cracks will diminish upon cooling. Larger cracks won’t close up, but
won’t affect enjoyment. (Trust me, I’ve eaten a hundred badly cracked ones
with the same cheesecake love. Just a slightly slumped baking heart!)

After 20 minutes, turn the heat down to 130°C (265°F). Open the
door for 10 seconds, fanning the cake to start the temperature
drop and release some steam. Close the door and bake for a further
30 minutes.

After this time, the cheesecake should have risen a few millimetres
over the lip of the tin. Turn the oven off. Open the door and fan for
10 seconds, then close and leave the cheesecake in the cooling oven
for 10 minutes.