Preheat your oven to 320°F (160°C). Line a 12-cup muffin tin with cupcake liners.

Combine cream cheese, butter, and milk in a medium saucepan over low heat. Stir until smooth and silky, then remove from heat and let it cool.

Whisk together flour, cornstarch, and salt in a separate bowl.

Mix egg yolks, sugar, and lemon juice (if using) in a large bowl. Whisk until pale and creamy, then add the cooled cheese mixture.

Sift in the dry ingredients and gently stir until the batter is smooth.

Beat the egg whites until soft peaks form. Gradually add 2 tbsp of sugar, whipping until stiff peaks form.

Fold a third of the beaten egg whites into the batter to lighten it, then fold in the remaining egg whites.

Pour the batter into cupcake liners, filling them about 3/4 full. Tap the pan lightly on the counter.

Bake for 20–25 minutes or until the tops are golden brown and slightly puffed.

Cool in the pan for about 5 minutes, then transfer to a wire rack.

Dust with powdered sugar if desired before serving.