French Onion Soup
["6 onions, shredded or sliced", "4 Tbsp. butter", "4 c. chicken stock (broth)", "2 c. beef broth", "3 or more slices dry French bread", "1 plus c. shredded mild Swiss cheese", "fresh grated Parmesan cheese (optional)"]
["Melt the butter in a large heavy saucepan and saute the onions over a low heat, stirring frequently, 20 to 30 minutes.", "Increase the heat, stir and saute the onions until they are golden brown. Add the broths and simmer 20 minutes."]
["onions", "butter", "chicken", "beef broth", "bread", "Swiss cheese", "Parmesan cheese"]