Directions

• Preheat a conventional oven to 160°C/320°F, with a rack in the lower-middle position; switch the fan off. Butter the 20 cm solid-bottom tin, line its base with a parchment circle and fit a buttered parchment collar about 2 cm above the rim. Set out a larger roasting tray, a kettle, a scale, two mixing bowls and an electric mixer. Separate the six eggs and measure all the ingredients before starting. Check that the roasting tray fits your oven before filling it. Leave room above the cake for its rise. Use an oven thermometer if your oven’s temperature is uncertain.
• Put the cream cheese, butter, milk and 40 g of the sugar in a heatproof bowl. Rest it over a saucepan of barely simmering water, keeping the bowl’s base above the water. Whisk gently until the cheese has no visible lumps and the butter is incorporated. Lift the bowl off the saucepan and let the mixture cool until just lukewarm, stirring occasionally. It must not be hot when the yolks go in. Keep water and steam out of the mixture. If small cheese lumps remain, smooth them now; aggressive mixing after adding the meringue would release the air needed for the rise.
• Whisk the yolks into the lukewarm base one at a time. Add the vanilla, lemon juice and zest. Sift the cake flour, cornstarch and salt over the bowl and whisk gently just until smooth. Scrape around the bowl and across its bottom. If there are stubborn lumps, pass the base through a fine sieve before proceeding; do not strain it after adding the meringue. The base should be cohesive and pourable. Avoid beating it for several minutes once the flour is wet. Set it aside while making the meringue, but do not start the whites until the base and pan are ready.
• In a completely clean, dry bowl, combine the six egg whites with the cream of tartar. Beat on medium speed until the whites are foamy throughout and no pool of clear liquid remains at the bottom. Begin adding the remaining 100 g caster sugar gradually in three or four additions, letting each addition mix in before the next. Keep the mixer moving around the bowl. A greasy bowl or a trace of yolk can interfere with the foam. Start again with clean equipment if the whites refuse to build volume; adding extra flour will not fix them.
• Continue beating at medium speed until the meringue is glossy and holds a soft-to-medium peak. Stop the motor, lift the beaters and look: the peak should stand at its base while its upper tip bends over. If it falls flat immediately, beat a little longer and check again. Stop before it becomes rigid, dry or clumpy. Use the finished meringue promptly. Follow the texture, not a fixed number of minutes: mixer power and egg temperature vary. The photograph shows the flexible tip to aim for. Do not keep beating simply to make the tallest possible peak.
• Stir one third of the meringue into the cheese base with a whisk to lighten it. Add half of the remaining meringue and switch to a spatula. Cut through the center, sweep along the bottom and lift the batter over itself, rotating the bowl. Fold in the final portion the same way. Stop once no white streaks or dense yellow pockets remain; the batter should still look airy. Reach the bottom on each pass, where the heavier cheese mixture tends to collect. Some white ribbons in this process photo show an intermediate stage; they should disappear before you pour.
• Pour the batter gently into the lined tin and level it lightly. Fill no higher than about two thirds of the tin itself, below its rim; bake any excess separately rather than overfilling. Pass a thin skewer through the batter in a few slow loops to release obvious large air pockets. Avoid repeatedly banging the tin on the counter or stirring the batter again. Check the surface for large trapped bubbles, not every tiny bubble. Fine air bubbles are part of the structure you have just created. Move to the water bath without letting the filled tin stand for a long time.
• Place the filled cake tin in the roasting tray on the oven rack. Carefully pour freshly boiled water into the outer tray to a depth of about 2 cm, keeping it below the cake-tin rim and away from the batter. Slide the rack in gently and close the door. Wear oven mitts and keep your face and hands clear of escaping steam. The water belongs around the tin, never inside it. Filling the outer tray on the rack avoids carrying a heavy, sloshing pan across the kitchen. This recipe uses a seamless tin, so foil waterproofing is not needed.
• Bake at 160°C/320°F for 20 minutes. Without opening the door, reduce to 150°C/300°F and bake for another 50–60 minutes. At the end, look for a golden top, set edges and a center that trembles gently rather than rippling like liquid. A skewer into the center should come out without wet batter. If still wet, continue in 5–10-minute increments at 150°C and check again. The normal bake is 70–80 minutes, but the doneness cues take priority. Avoid opening the oven during the early rise. If the top darkens too quickly late in baking, cover it loosely with foil without pressing on the surface.
• When baked through, turn off the oven and leave the cake inside with the door slightly ajar for 20 minutes. Remove the tin from the water bath and cool on a rack for about 10 minutes, until safe to handle. Loosen the parchment, gently invert onto a parchment-covered plate, remove the tin and base paper, then immediately turn upright onto a serving plate. Let it finish cooling, then refrigerate for at least 4 hours. Slice with a warm, wiped knife. Allow about 1 hour total for oven rest and cooling before refrigeration; do not leave this dairy-and-egg cake at room temperature for more than 2 hours after baking. Some settling is expected. If the cake is too fragile to unmold warm, cool it in its tin and handle it gently once firmer.