Preheat oven to 320°F (160°C). Line a 12-cup muffin pan with cupcake liners and prepare a water bath.

In a double boiler, melt cream cheese, butter, and milk until smooth. Let cool slightly.

Add egg yolks, vanilla extract, lemon juice, and salt to the mixture. Sift in flour and cornstarch, mixing gently.

Beat egg whites until frothy, gradually adding sugar until stiff peaks form.

Fold 1/3 of egg whites into cream cheese mixture, then fold in the rest carefully.

Pour batter into cupcake liners, filling 3/4 full. Tap gently to release air bubbles.

Place pan in water bath and bake 25–30 minutes until lightly golden and set.

Cool cupcakes in oven for 10 minutes, then transfer to wire rack. Dust with powdered sugar before serving.