Melt the cream cheese and butter together in a heatproof bowl set over a simmering pot of water (double boiler), stirring occasionally until smooth. Alternatively, microwave in 30-second intervals, stirring in between, until melted and smooth.

Remove from heat and whisk in the milk until well combined.

Whisk in the egg yolks one at a time, making sure each yolk is fully incorporated before adding the next.

Stir in the lemon juice.

Sift together the cake flour and cornstarch.

Gradually add the sifted dry ingredients to the wet ingredients, whisking until just combined. Be careful not to overmix.

In a clean, grease-free bowl, beat the egg whites with an electric mixer until soft peaks form.

Gradually add the sugar, one tablespoon at a time, while continuing to beat the egg whites.

Beat until stiff, glossy peaks form. The meringue should hold its shape but not be dry.

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

Gently fold in the remaining meringue in two additions, being careful not to deflate the meringue.

Line a muffin tin with cupcake liners.

Divide the batter evenly among the cupcake liners, filling them almost to the top.

Place the muffin tin in a larger baking pan.

Pour hot water into the larger pan, reaching about halfway up the sides of the muffin tin.

Bake in a preheated oven at 320°F (160°C) for 25-30 minutes, or until the tops are lightly golden brown and a toothpick inserted into the center comes out with a few moist crumbs.

Turn off the oven and crack the oven door slightly. Let the cheesecakes cool in the oven for 30 minutes.

Remove the cupcakes from the water bath and let them cool completely at room temperature.

Chill them in the refrigerator for at least 2 hours before serving.