1. Preheat your oven to 320°F (160°C). Line a 12-cup muffin tin with cupcake liners.
2. In a medium heatproof bowl, combine the softened cream cheese, butter, and milk. Set the bowl over a pot of gently simmering water (double boiler method) and stir until smooth and warm to the touch. Remove from heat and let cool slightly.
3. Whisk the egg yolks into the cream cheese mixture one at a time, ensuring each is fully incorporated. Stir in the vanilla extract.
4. Sift the cake flour and cornstarch together, then gently fold them into the cream cheese mixture until just combined. Be careful not to overmix.
5. In a clean, dry bowl, beat the egg whites with cream of tartar using an electric mixer on medium speed until foamy. Gradually add half of the granulated sugar and continue beating until soft peaks form.
6. Increase the mixer speed to high and slowly add the remaining sugar. Beat until stiff, glossy peaks form.
7. Fold one-third of the meringue into the cream cheese batter gently to lighten the mixture. Then carefully fold in the remaining meringue in two additions, preserving as much air as possible.
8. Divide the batter evenly among the cupcake liners, filling each about 3/4 full. Tap the pan lightly on the counter to release any large air bubbles.
9. Place the muffin tin inside a larger roasting pan. Fill the roasting pan with hot water halfway up the sides of the muffin tin to create a water bath. This ensures a moist, even bake.
10. Bake for 25-30 minutes, or until the tops are lightly golden and a toothpick inserted into the center comes out clean.
11. Turn off the oven and leave the cupcakes inside with the door slightly ajar for 15 minutes to prevent sudden temperature changes that cause cracking.
12. Remove from the oven and water bath, then cool completely on a wire rack before serving.

“One of the sweetest memories I have is watching Mama Lou gently fold the meringue into the batter, whispering that ‘patience and softness make the best cakes.’ This step truly makes or breaks the texture of these cupcakes.”