Classic French Onion Soup made with red onions and 4 types of cheese. Rich homemade caramelized onion broth is added to each bowl with a slice of toasted French bread, and then provolone, swiss, mozzarella and parmesan is melted on top. Broil until browned and bubbly and enjoy!
Melt butter in a large pot over medium high heat. Add slices of red onions and sprinkle salt on top of them. Stir until the onions are caramelized and syrupy, about 30 minutes.
Add beef broth, chicken broth, Worcestershire sauce, thyme, bay leaf and salt and pepper into the pot, stirring and then allow to simmer for 15 minutes. Discard bay leaf.
Preheat oven to BROIL.
Ladle soup into 4 oven-safe bowls evenly. Place 1 slice of toasted French bread on top of each (you can keep it whole or rip it up into pieces). Add 1 slice of provolone, ½ slice Swiss cheese, 1 tablespoon mozzarella cheese and 1 tablespoon Parmesan cheese on each piece of bread. Add a pinch of paprika on top.
Place bowls on a baking sheet and broil in the oven until cheese bubbles and lightly browns, about 3-4 minutes.
Remove from oven and serve. Enjoy this delicious French Onion Soup!