Sprinkle the yeast over very warm water in a large bowl (very warm water should feel comfortably warm when dropped on wrist). Stir until yeast dissolves.
Add sugar, the 1/4 cup butter or margarine and salt to hot milk and stir until the sugar dissolves and butter or margarine is melted. Cool mixture to 105 to 115 degrees.
Add milk mixture to yeast, then beat in egg. Beat in 4 cups of the flour, 1 cup at a time, to form a soft dough. Use some of the remaining 1/2 cup of the flour to dust a pastry cloth.
Knead the dough lightly for 5 minutes, working in the remaining flour (use it for flouring the pastry cloth and your hands).
Place dough in a warm buttered bowl; turn greased side up. Cover and let rise in a warm place until doubled in bulk, about 1 1/4 to 1 1/2 hours.
Punch dough down and knead 4 to 5 minutes on a lightly floured pastry cloth. Dough will be sticky, but use as little flour as possible for flouring your hands and the pastry cloth, otherwise the rolls will not be as feathery light as they should be.
Pinch off small chunks of dough and shape into round rolls about 1 1/2 to 1 3/4 inches in diameter. Place in neat rows, not quite touching, in a well-buttered 13x9x2 inch pan. Cover rolls and let rise in a warm place until doubled in bulk, 30 to 40 minutes.
Brush tops of rolls with melted butter or margarine, then bake in a 375 degree oven for 18 to 20 minutes or until nicely browned. Serve warm with plenty of butter.