Preheat oven to 320°F (160°C). Grease and line a 7 or 8-inch round cake pan with parchment paper. Wrap the outside with foil to make it waterproof. Prepare a large tray for a water bath.

In a heatproof bowl over a double boiler, whisk together cream cheese, butter, and milk until smooth. Remove from heat and let cool slightly. Mix in egg yolks, one at a time, then add vanilla extract and lemon juice. Stir until combined. Sift in the cake flour and cornstarch. Gently fold to make a smooth batter.

In a clean, grease-free bowl, beat egg whites with a pinch of salt until foamy. Gradually add sugar while beating, until stiff peaks form (the meringue should be glossy).

Gently fold one-third of the meringue into the cream cheese mixture to lighten it. Fold in the remaining meringue in two additions, being careful not to deflate the batter.

Pour the batter into the prepared pan. Tap the pan gently to remove air bubbles. Place the pan in the large tray. Add hot water to the tray, filling it about 1 inch deep. Bake at 320°F (160°C) for 25 minutes, then lower the temperature to 280°F (140°C) and bake for another 55-60 minutes.

Turn off the oven and leave the cake inside with the door slightly open for 15-20 minutes to prevent sudden shrinkage. Remove the cake from the oven and let it cool completely before removing it from the pan.

Dust with powdered sugar or serve with whipped cream, fresh berries, or a drizzle of fruit sauce.