Make a dough with 1 kg flour, 300g sugar, 200g butter, 3 whole eggs and 2 extra yolks, the grated rind of 1 lemon, 100g fresh yeast. Knead well. Cover the dough and leave it in a warm place overnight. The next day, cut the dough in two, score a cross into the surface, brush with the two lightly beaten egg whites and sprinkle a little sugar over the top. Bake in the oven at 160°C.