Julienne the Vidalia Onion (5).
Melt the Butter (3 tablespoon) in a large deep pot (preferably Dutch oven) over medium heat. Add the onions and cook until caramelized, about 20 minutes. Stir with a wooden spoon to ensure no onions stick to the pot.
While onions cook, you can slice the Baguette (1).
Deglaze the pot with 1 cup of the Beef Stock (1 quart), then cook until dry. Repeat 2 more times until the onions are dark brown and have absorbed most of the stock.
Roughly chop the Fresh Thyme (1 tablespoon).
Add the thyme, remaining beef stock, and Chicken Stock (1 quart) and simmer for 20 minutes. Add Salt and Pepper (to taste) and adjust as needed. Add the Dry Sherry (1/4 cup) and stir to combine.
Portion into soup bowls, add 2 slices of bread, top each bowl with a slice of Provolone Cheese (4 slice), then place under the broiler until cheese is golden brown.