Mix flour, yeast, sugar, and salt, keeping salt from directly touching yeast. Add milk and eggs gradually; knead until soft and smooth.

Shape dough into a ball and let rise in a warm place for 1 hour, until doubled. Deflate gently and chill for 30 minutes.

Roll dough on a floured surface. Place butter in the center, leaving a clear border, then fold dough around butter and seal edges.

Roll into a long rectangle. Fold both short ends toward the center, then fold in half. Turn dough so the fold is on the right.

Roll and repeat the fold once more. Chill 30 minutes, or longer if butter becomes soft.

Roll dough into a 40-by-50-centimeter rectangle. Cut into two strips and then into triangles.

Roll each triangle from the wide end toward the point. Arrange on two lined baking sheets, about 9 per tray.

Let rise about 1 hour. Brush with egg wash, then bake at 410°F (210°C) for 10 to 15 minutes, until deeply golden.