Butter a 15 cm round springform pan with a little extra butter. Line the bottom with parchment paper, leaving it overhanging by about 3 cm, then wrap the outside of the pan with a double layer of aluminum foil to keep water out.

Sift the flour and cornstarch together, preheat the oven to 160°C (air fryer 140°C), and bring water to a boil for the water bath.

Put the cream cheese, butter, and milk in a heatproof bowl, then heat over a double boiler (or microwave at 600 W for 1 min to 1 min 30) and stir until completely smooth.

Add the egg yolks one at a time, mixing after each addition, then add the lemon juice. Whisk in the sifted dry ingredients until no lumps remain (optional: strain the batter through a sieve for an even smoother texture).

Beat the egg whites with an electric mixer, adding the sugar in 3 additions, until soft peaks form (the tip folds over like a bird’s beak).

Whisk in 1/3 of the meringue to the cream cheese base to loosen, then fold in the rest in 2 additions with a spatula, gently lifting from the bottom without deflating the bubbles.

Bake in a water bath: 20 min at 160°C (air fryer 140°C), then reduce to 140°C (air fryer 120°C) and bake another 40 to 50 min. Tent with aluminum foil if it browns too quickly. It’s done when the top is golden and a skewer comes out without wet batter.

Turn off the oven and leave the cake inside, door ajar, about 15 min. Remove, let cool, then refrigerate in the pan for at least half a day (ideally longer) before unmolding.