Yield: 2 Loaves
Stir the yeast into the warm water (or milk), with the salt and sugar. Set aside for five minutes to dissolve. Put the flour in a bowl and make a well in it. Put the eggs and the yeast mixture in the well. Mix it, drawing in the flour, to make a soft, sticky dough.
Work the dough, lifting and slapping, until it becomes soft and very smooth and elastic (this process is a long and difficult job by hand. A mixer with hook attachment is great if you have one). Knead the butter to soften it to the same texture as the dough. Now, work in the butter a piece at a time, again to create smooth, sticky dough (again, the mixer will make that easy). Let the dough rise at room temperature in a covered bowl for two hours.
Punch down the risen dough. Put it back in a bowl, cover, and refrigerate overnight to double. Shape the bread; let it rise 1 1/2 hours in the pan. Glaze with yolk and milk wash. Bake the loaves at 425ºF/220°C for 40 to 45 minutes.