French Onion Soup is one of my favorites, too.
Slice about six large, sweet onions (it looks like a lot, but they cook way down). Place in a large pan with a couple of tablespoons of butter, 2 bay leaves, 2 teaspoons of dried thyme, some freshly ground black pepper, and 2 tablespoons of chopped garlic. Cook over low heat (do not brown), stirring frequently until onions are soft and reduced in volume. Add 1 1/2 tablespoons each of flour and worchestershire sauce. Stir. Add 2/3 cup of burgundy wine, increase heat, bring to a boil. Add 2 1/2 quarts of beef stock. Simmer for 20 minutes. Taste to check for levels of pepper, worchestershire, and thyme.
Place a slice of toasted french or Italian bread in the bottom of each bowl. Top with soup, then cheese (a swiss cheese, like gruyere, is commonly used, but a good mozzarella can be really tasty, too!!). Place bowl under broiler until the cheese is lightly browned and bubbly. Enjoy!
(It's also good with mushrooms added- slice them up and cook with the onions.)