Preheat the oven to 320°F (160°C).

In a mixing bowl, blend the cream cheese and unsalted butter until smooth.

Add the whole milk, granulated sugar, and lemon juice, mixing until combined.

Separate the eggs, adding the yolks to the mixture and ensuring everything is well blended.

Sift together the flour, cornstarch, and salt, then gradually incorporate it into the cream cheese mixture.

In a separate bowl, beat the egg whites until stiff peaks form, then gently fold into the batter.

Pour the batter into cupcake liners in a muffin tin.

Bake for about 25 minutes, or until the tops are golden and a toothpick comes out clean.

Let the cupcakes cool before dusting with powdered sugar (if desired).