Preheat the oven to 320°F (160°C). Line a muffin tin with cupcake liners or parchment paper.
In a mixing bowl, beat the softened cream cheese with granulated sugar until smooth. Add the milk, egg yolks, and vanilla extract, mixing well to combine.
Sift in the all-purpose flour and cornstarch, and mix until there are no lumps.
In a separate bowl, beat the egg whites and salt until soft peaks form. Gradually add the granulated sugar (from the egg whites) while continuing to beat until stiff peaks form.
Gently fold the whipped egg whites into the cream cheese mixture in three additions, being careful not to deflate the mixture.
Divide the batter evenly among the cupcake liners, filling them about ⅔ full.
Bake in the preheated oven for 30 minutes, or until the tops are lightly golden and the centers are set.
Remove from the oven and let cool completely in the tin.
Once cooled, dust the tops with powdered sugar and serve.