In a bowl, combine egg yolks and Natvia. Beat until pale and creamy in appearance.
Add milk, flour, lemon rind and lemon juice.
In another bowl, beat egg whites to soft peaks. Add in extra half tablespoon of Natvia and beat until well dissolved.
Fold whites gently into yolk mixture. Divide mixture into four well-greased ramekins. Place ramekins into baking dish filled with a little water. Bake pudding in the oven for 30-35 minutes. Puddings should jiggle a little when ready.