- Preheat your oven to 300°F. Line an 8-inch round cake pan with parchment paper. Wrap the outside with foil to prevent water from seeping in. 
- Melt the cream cheese and butter together over a double boiler until smooth. Gradually whisk in the warm milk. Let it cool slightly. 
- Add the egg yolks to the cream cheese mixture and whisk until combined. Sift in the flour, cornstarch, and salt. Stir gently until smooth. 
- In a separate bowl, beat egg whites until frothy. Add cream of tartar, then slowly add the sugar. Beat until stiff peaks form. 
- Fold the meringue into the batter in three additions, mixing gently to keep the volume. 
- Pour the batter into the prepared pan. Place the pan in a larger pan filled with 1 inch of hot water. 
- Bake for 1 hour 10 minutes, or until golden on top and set. Let it sit in the oven with the door slightly ajar for 15 minutes. 
- Cool completely before removing from the pan. Chill for at least 4 hours before slicing.