In a bowl, soften yeast in water. Add milk, salt, sugar, egg and 1 C of flour. Beat to make a smooth batter and blend in melted butter; set aside.

In a large bowl, cut the 1 C firm butter into remaining 4 C flour until butter particles are the size of kidney beans. Pour yeast batter over top and carefully turn the mixture over with a spatula to blend just until all flour is moistened. Cover with clear plastic film and refrigerate until well chilled - at least 4 hours or up to 4 days.

Remove dough to a floured board, press into a compact ball and knead about 6 turns to release air bubbles. Divide dough into 4 equal parts. Shape one part at a time, leaving remaining dough wrapped in plastic in refrigerator.

To shape croissants: Roll one part of the dough on a floured board into a circle 17 inches in diameter. Using a sharp knife, cut the circle into 8 equal pie-shaped wedges.

For each croissant, loosely roll wedges toward the point. Shape each roll into a crescent and place on an ungreased baking sheet with the point down; allow at least 1-1/2 inches of space around each croissant.

Cover lightly and let rise at room temperature in a draft-free place. (Do not speed the rising of the rolls by placing them in a warm spot, as the butter will melt and ooze out unattractively.) When almost doubled in bulk (2 hrs) brush with egg wash. Bake at 325 for about 35 minutes or until lightly browned. Makes 32.

Freeze the rolls, tightly wrapped. To reheat, arrange rolls in single layer on baking sheet and bake, uncovered in 350 oven for about 10 minutes.