Preheat oven to 320°F (160°C). Line the bottom and sides of an 8-inch round cake pan with parchment paper, extending the paper 2 inches above the rim.

In a double boiler or a bowl over simmering water, melt cream cheese, butter, and milk together until smooth. Let it cool slightly.

Whisk in the egg yolks, lemon juice, and vanilla extract until well combined.

Sift in the cake flour and cornstarch. Whisk gently until the batter is smooth and no lumps remain.

In a clean, grease-free bowl, whisk egg whites and cream of tartar until foamy.

Gradually add sugar while whisking on medium-high speed until soft peaks form. Do not overbeat to stiff peaks.

Gently fold 1/3 of the meringue into the cheese batter to lighten it.

Pour the mixture back into the remaining meringue and fold very gently with a spatula until just combined.

Pour the batter into the prepared pan and tap it on the counter to release large air bubbles.

Place the pan in a larger baking tray filled with 1 inch of hot water (bain-marie).

Bake at 320°F (160°C) for 20 minutes, then reduce to 285°F (140°C) for 40-50 minutes until golden and set.

Turn off the oven and leave the door slightly ajar for 15 minutes to prevent the cake from collapsing.

Remove from the oven and let it cool completely in the pan before unmolding.

Chill in the refrigerator for at least 4 hours (or overnight) for the best texture. Dust with powdered sugar before serving.