Put the dried yeast, butter, egg, sugar, salt and flour in a bowl. Add the water slowly, only 150ml at first, then the rest if necessary. Not all of the water, or a little more water than indicated, may be needed to make the dough. Cover and let the dough rise in a warm place for 1 hour.
Now place the dough on a floured work surface and knead it so that the air can escape.
Shape 8 balls of the same size and place them on a baking tray lined with baking paper with a little space between them. The balls should have a smooth surface without seams, otherwise they will tear open during baking. Press the balls a little flat with your hand and cover and let rise for another hour.
Mix the egg white with 1 tablespoon of water and brush the dough blanks with it.
Bake at 185 ° C top / bottom heat for about 12-17 minutes, until they have turned slightly color.
Allow to cool on a wire rack and cover as desired.