Preheat oven to 320°F (160°C). Line a muffin tin with cupcake liners and place a baking dish filled with hot water on the lower oven rack.

In a heatproof bowl over simmering water, melt cream cheese, butter, and milk together until smooth.

Remove from heat and whisk in egg yolks, vanilla extract, and lemon juice.

Sift in cake flour, cornstarch, and salt. Mix until silky smooth.

In a clean bowl, beat egg whites until foamy. Gradually add sugar and whip until soft to medium peaks form.

Fold one-third of the whipped egg whites into the cream cheese batter, then gently fold in the remaining meringue.

Pour batter into cupcake liners, filling each about 80% full.

Bake for 22–25 minutes until lightly golden and slightly jiggly in the center.

Turn off oven, crack the oven door slightly, and let cupcakes cool inside for 10 minutes.

Cool completely, refrigerate for at least 2 hours, then dust with powdered sugar before serving.