French onion soup casserole

1. Melt butter in a large saucepan over low heat. Add onions and cover. Cook for about 30 minutes, stirring occasionally.

2. Add the beef broth and the Worcestershire sauce to the onions. Heat the broth mixture until it boils and then reduce heat to low. Simmer, uncovered, for about 30 minutes. The broth will reduce greatly.

3. Pour onion and broth mixture into a greased casserole dish.

4. Lightly toast the slices of bread. Place toasted bread in a single layer on top of onion/broth mixture spaced evenly.

5. Cover bread with a thick layer of the shredded mozzarella and top with grated Parmesan.

6. Bake, uncovered, in a 350 degree oven for 20 to 30 minutes, or until cheese is melted and brown on top.