Blen together 1/2 cup butter, parsley, garlic, rosemary and pepper. On waxed paper, form patty 1 inch thick; place in freezer until firm. Meanwhile flatten chicken breasts with meat hammer or edge of heavy saucer to 1/4 inch thickness. Cut butter into 6 equal pieces, place one in centre of each breast. Tuck in ends and roll out tightly. Secure with toothpicks or skewers. Dip in egg and then in bread crumbs. Chill. In saucepan, cook onion with parsley in 2 tablespoons of butter until tender. Blend in soup, milk and sherry. Heat; stir occasionally. Fry 2 breast rolls at a time in deep fat at 350 degrees for 10-12 minutes until well browned. Drain on absorbant paper, serve with sauce.