In the 17th century, the Visitandine sisters of Nancy, of the Order of the Visitation of Holy Mary, used the surplus egg whites to make this cake. The yolks being used at that time for the illuminations of religious books. A light cake very easy to make, delicious with custard.
1. In a large bowl, beat the egg whites until you get some foam. Then add the sugar to the egg whites in 3 steps and continue beating until all becomes stiff.
2. In another large bowl, gently pour the warm melted butter, flour, ground almonds, vanilla and lemon zest and mix well together.
3. Pour the white egg part to the bowl of mixtures in 4 steps. Gently mix together. Don't overmix not to break the egg whites foam.
4. Butter a round, flat mold and pour in the preparation.
5. Bake in a low oven (150°C) for 35 to 40 minutes.
6. Unmold the cake and let it cool on a wire rack.