Preheat your oven to 320°F (160°C) and line a standard muffin tin with tall paper liners. Place a shallow roasting pan on the lower rack for the water bath.

In a large bowl, beat softened cream cheese and butter until smooth and free of lumps. Add the egg yolks one at a time, mixing after each. Add half of the sugar, milk, vanilla, and lemon juice. Beat until glossy and smooth.

Sift the flour and salt over the mix and fold in gently until no streaks remain.

In a clean bowl, beat the egg whites with cream of tartar until foamy. Add the remaining sugar in two parts and whip to soft or medium peaks.

Take a scoop of the whipped whites and fold it into the cream cheese base to loosen it. Then fold the mix back into the whites in 3 additions.

Spoon batter into liners until 3/4 full. Place warm water in the lower pan so it reaches about halfway up the muffin tin.

Bake for 20–25 minutes until the tops are lightly golden and a toothpick inserted near the center comes out with a few moist crumbs.

Turn off the oven, open the door half an inch, and leave the cupcakes inside for 10 minutes to avoid a quick temperature change. Remove and cool completely on a rack.

Dust with powdered sugar or cocoa before serving. Serve at room temperature or chilled.