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

In a medium saucepan over low heat, combine cream cheese, unsalted butter, and whole milk, whisking until smooth for about 5-7 minutes. Let it cool to room temperature.

In a separate bowl, sift together all-purpose flour, cornstarch, and salt. Set aside.

In another bowl, whisk egg yolks, granulated sugar, and lemon juice until pale and fluffy, about 3-5 minutes. Gradually mix in the cooled cream cheese mixture.

Sift the dry ingredients into the egg yolk mixture and gently stir until fully blended.

In a clean bowl, beat egg whites until soft peaks form, then gradually add sugar until stiff peaks are achieved.

Fold one-third of the beaten egg whites into the batter, then gently fold in the remaining egg whites until no streaks remain.

Fill the muffin tin with batter, about three-quarters full, and tap gently to remove air bubbles.

Bake in the preheated oven for 20-25 minutes until golden brown and puffed.

Let the cupcakes cool in the tin for 5 minutes before transferring to a wire rack. Dust with powdered sugar before serving.