Preparation

Heat the oven to 320°F and move the rack to the middle of the oven. Lightly butter and line the bottom and sides a 6 inch cake pan with parchment paper. I made a sling as well, but found that it was much easier to just tip the cake out onto my hand after it cooled a bit. Do what you think will work for you.

In a double boiler, stir together the cream cheese, butter, and milk until the cream cheese melts and everything is smooth and incorporated. Remove from the heat and let cool completely, stirring to help cool faster. Bring a pot of water to a boil – this will be for the water bath. Keep it at a simmer while you prep the cake.

Separate the eggs, putting the whites in the bowl of a stand mixer. Place the bowl of whites in the fridge to chill. When the cream cheese is cool, sift in the flour and cornstarch and whisk until thoroughly combined. Whisk in the egg yolks until smooth and combined.

Whip the egg whites with the cream of tartar until frothy and pale, adding in the sugar in bit at a time until the whites are whipped into a glossy thick soft peak meringue – one that holds its shape, with a beak that folds over on itself. Be careful not to over whip. Add 1/3 of the whipped egg whites to the yolks and using a whisk, gently incorporate. Add another 1/3 of the whites and whisk again, being careful not to deflate. Transfer the egg yolk mixture to the remaining egg whites. Whisk together and then use a spatula to fold together.

Gently pour the batter into the prepared pan and then tap it against the counter couple times to force the air bubbles to come to the top. Place into a deep baking dish and carefully pour the hot water 3/4 of the way up the pan. Place the entire thing in the oven and bake for 30-40 minutes keeping an eye on it. If it starts to crack, it may be that your oven is too hot, so lower it by 20 degrees or so.

The cake will be done with the top is golden and it springs back when you gently press it. Crack open the oven door and let the cake cool in the water bath for about 15-20 minutes, then remove from the oven and let cool, in the water bath for another 10 minutes or so. At this point it should be cool enough to remove from the pan. Run a butter knife or offset spatula around the edges and then flip the cake onto your hand, then flip back right side up onto a wire rack to cool. Dust with icing sugar if desired, slice and enjoy!