French Onion Soup Casserole
1. Melt butter in a large saucepan over low heat. Add onions and cover. Cook for 30 minutes and stir from time to time.
2. Add the beef broth and Worcestershire sauce. Heat the broth until it boils. Reduce heat to low and let is simmer (uncovered) for 30 minutes. The broth will reduce.
3. Lightly toast the bread slices.
4. Pour the onion and broth mix into a greased casserole dish. Cover bread with the bread and top with shredded mozzarella and Parmesan cheese.
5. Bake (uncovered) at 350 for 20 minutes (Until cheese is melted and brown on top).