French Onion Soup

I accidentally bought too many onions at the grocery store last week. I already had a whole bag at home so I figured onion soup would be a good way to use a lot of onions in one recipe. Turns out onion soup recipes were popular this week in various publications I read -- including NYT, Main Street Magazine (pg 17), and a few others -- so I created an amalgamation of the various recipes.
And I have to say...the result was amazing!

INGREDIENTS

• 2-3 tablespoons unsalted butter
• 1 slice uncooked bacon (diced)
• 4 medium-large yellow onions (about 3 pounds), peeled and thinly sliced (using a food processor will save on tears :)
• 1 teaspoon kosher salt, plus more to taste
• 1 3/4 quarts beef stock (7 cups)* I used chicken stock and added a tablespoon of Beef Better Than Bouillon while warming the broth)
  
• 2/3 cup dry white wine
• 1/3 cup dry sherry
• 1-2 tablespoons Wondra flour
  
• 3-4 sprigs of fresh thyme
• 2 bay leaves
• 2-3 tablespoons of Worcester sauce
• 1/4 teaspoon black pepper, plus more to taste
• 1½ cups grated Gruyère cheese (I didn't have Gruyère cheese on hand so I combined Jarlsberg & Parmesan cheese...LOVED IT)
  
• 6 - 1 inch thick slices of ciabatta bread (or use French baguette)

DIRECTIONS

1. Melt butter in a heavy Dutch oven over medium heat.  Add the bacon and onions and 1 teaspoon salt, stir and cover for 5 minutes. Remove lid and let onions caramelize until golden brown over medium heat, stirring occasionally. Adjust heat if onions are browning too quickly. The caramelization process can take awhile...45 to 60 minutes.
2. In the meantime, put the broth, the bay leaf, the thyme sprigs and the Worcester sauce in a saucepan over low heat.
3. Once onions are caramelized, add wine, sherry and a few splashes of Worcester sauce to the pot and bring to a boil. Stir in flour until the mixture thickens (1-2 minutes).
4. To the onion mixture, slowly add warm broth slowly plus 1/2 teaspoon salt and some pepper and boil uncovered for 10 minutes. Add more salt and pepper to taste.
5. Preheat the broiler and arrange individual ovenproof bowls on a baking sheet. Ladle soup into the bowls and cover the top with bread slices. Sprinkle each generously with the cheese
6. Broil for a minute or two (keep an eye on it) until the cheese melts and browns. Serve immediately.