Preheat oven to 350 degrees F.
Beat butter with sugar until well blended. Add two egg yolks; add juice and rind of lemon. Follow with flour and mix well; add milk and blend. Whip egg whites until stiff. Gently blend egg whites with batter.
Pour mixture into a large measuring cup for ease of pouring into custard cups or ramekins. Place filled cups into a bain-marie (water bath).
Bake for 30 to 40 minutes. Should be slightly brown on top.
Variation: Use Jasmine-infused sugar in place of regular granulated sugar.
Source: The manager of the Curves I was attending asked me to do a recipe book based on submissions from the members. This was one of the recipes in it.
By sooz from Bradford, ON