Butter ramekins(6), put the ramekins in a large oven proof cake pan, fill have way with very hit water, in a large mixing bowl, cream softenwd butter. Add sugar, flour, salt, lemon rind and juice. Mix well.
In a separate bowl mix egg yolks, stir in milk. Slowly add egg mixture to the butter mixture.
Beat egg whites until stiff, gently fold the egg whited into the mixture.
Pour mixture into ramekins, carefully put in oven and bake for 45 mins.