French Onion Soup

Name: French Onion Soup
Ingredients: 2 tablespoons extra-virgin olive oil; 2 tablespoons unsalted butter; 2 large yellow onions, thinly sliced; 2 large sweet onions, thinly sliced; 1 tablespoon water; ½ cup dry white wine; ¼ cup dry vermouth; 2 tablespoons all-purpose flour; 8 cups unsalted beef broth, at room temperature; 2 tablespoons chopped fresh thyme; 2 small cloves garlic, grated; ½ teaspoon ground pepper; ¼ teaspoon salt; 1 bay leaf; 2 tablespoons chopped fresh chives, plus more for garnish; 2 tablespoons chopped fresh flat-leaf parsley, plus more for garnish; 6 (1-inch) slices whole-wheat country bread, toasted; 1 cup shredded Gruyère cheese