Sprinkle the yeast over the like warm water and let sit for 5 min.
Sift the flour, salt and sugar into a bowl. Make a well in the center and add the eggs and yeast mixture. Stir well to form a loose dough, turn out onto a lightly floured surface and work the softened butter until the dough is smooth. Transfer to a bowl, cover with plastic and allow to rise in warm place for 1-1/2 hours.
Punch down dough, recover and set in refrigerator overnight.
Punch down dough with floured hands and knead lightly to remove air. Shape into 12 equal balls of dough. Place balls in a springform pan. Cover with plastic wrap and leave to rise for 1 hour.
Brush with egg glaze. Bake in a 400º oven for 40 minutes or until it sounds hollow when tapped. Turn out on wire rack to cool.