French Onion Soup

Name: French Onion Soup
Ingredients: 2 tablespoons olive oil; 6 medium yellow onions, sliced thin; 4 tablespoons (1/2 stick) butter; 4 sprigs fresh thyme; 2 bay leaves; 1 tablespoon flour; 1 cup dry white wine; Kosher salt; 6 cups Homemade Beef Stock, recipe follows; 4 sourdough boules, each about 1 pound, and 10 inches in diameter; 2 cups grated Gruyere cheese; 2- 3 tablespoons olive oil; 5 pounds meaty beef bones, such as shank bones; 4 carrots, halved; 4 stalks celery, halved; 2 large yellow onions, halved; 1 head garlic, halved; 1 teaspoon black peppercorns