Stir warm milk and sugar together. Add yeast. Let stand 10 minutes. Stir well. Add flour; beat well. Add milk, sugar and egg. Beat until smooth. Add butter; beat and set aside. In a large mixing bowl, place the 4 cups of flour and the chilled butter. Cut butter into flour until pieces are the size of beans (not too small). Pour the liquid batter into the flour mixture; stir until moistened. Cover the bowl with plastic wrap. Refrigerate for at least 4 hours or overnight. Remove from refrigerator. Press into a compact ball on a floured board and divide into 4 parts. Roll each into a circle 30 cm or 41 cm. Cut each circle into 6 or 8 pie-shaped wedges. For each croissant roll a wedge towards the point. Shape into a crescent and place on ungreased baking sheet. Let rise at room temperature until doubled. (May take 2 hours or more). Brush each with egg beaten with cold water. Preheat oven to 200ºC . Place croissants in oven. Lower temperature to 180ºC and bake for 15 20 minutes until golden. Makes 24 32.