-
In a bowl, mix egg whites with 1 tsp lemon juice until stiff.
-
In another bowl, beat the egg yolks with water, sugar and vanilla until light. Add melted butter and beat for another minute. Add the flour and mix it in.
-
Then add the lukewarm milk (if it is not lukewarm, the butter will harden), lemon juice and zest and beat until well incorporated.
-
Using a spatula, gently fold in beaten egg whites.
-
Pour the batter in paper-lined cupcake pan (standard size pan for 12 cupcakes), filling right to rim. Bake in preheated 325 F oven for about 30 minutes or until the top is golden.
-
Cool for at least 3 hours before serving. Serve sprinkled with powdered sugar.