Preheat your oven to 320°F (160°C). In a bowl, mix cream cheese and milk until smooth. Add sugar and stir until dissolved. Sift in flour and mix gently. Fold in lemon zest.

Beat egg whites in a clean bowl until stiff peaks form, approximately 5–7 minutes.

Fold whipped egg whites into the cream cheese batter in three portions, being careful not to deflate the mixture.

Line cupcake tin with liners, fill with batter, and place in a water bath. Bake for 25–30 minutes until tops are lightly golden.

Let cupcakes cool in the oven with the door ajar for 15 minutes, then transfer to a wire rack to cool completely.