Baked Vanilla Cheesecake

Heat the oven to 180C/350F.

Butter a 23cm springform tin and line the base with baking paper.

Crush the digestives to fine crumbs in a bag with a rolling pin, or in a food processor.

Stir the crumbs with the melted butter and the 3g of fine salt until every crumb is damp and a handful holds together when squeezed.

Tip the crumbs into the tin and press them into an even layer across the base with the flat bottom of a glass.

Bake for 10 minutes, until the base smells toasted and looks dry.

Set the tin aside to cool while you make the filling.

Turn the oven down to 150C/300F.

Beat the cream cheese on low speed for 1-2 minutes, until it is completely smooth.

Keep the mixer on low from here to the end. Air beaten into the batter expands in the oven and collapses as the cake cools, and that collapse is what tears the surface open.

Beat in the caster sugar and the cornflour.

Beat in the eggs and the yolk one at a time, scraping the bowl down between each.

Beat in the soured cream, vanilla, lemon zest and the 2g of fine salt, until the batter is smooth and pourable.

Pour the batter over the cooled base.

Tap the tin once on the worktop to bring the large bubbles to the surface.

Set a roasting tin on the shelf below and pour the boiling water into it. The steam keeps the oven damp, which stops the surface drying and setting hard before the middle has finished.

Bake for 60-75 minutes, until the outer 5cm is set and slightly risen and the middle 8cm still wobbles as one piece when you tap the tin.

Take it out while the middle still moves. A cheesecake baked until the centre is firm is dry and grainy by the time it is cold, and it cracks as it contracts.

Turn the oven off, prop the door open with a wooden spoon and leave the cheesecake inside for an hour.

Run a thin knife around the inside of the tin while the cake is still warm, so it can shrink without pulling at the edge.

Cool it to room temperature on a rack, about another hour.

Refrigerate for at least 6 hours, and overnight if you can. This is not a finishing touch: warm, the cake is a batter that has only just set, and it needs the whole time in the fridge to firm into something that cuts.

Release the ring.

Cut with a knife dipped in hot water and wiped dry between every slice.

Keep the spare egg white in the fridge for up to a week, or freeze it. Three more and it is a pavlova.