French Onion Soup

INGREDIENTS

• 2 Tbs. unsalted butter
• 2 1/2 lbs. yellow onions, halved and thinly sliced
• 1 Tbs. all-purpose flour
• 1 cup dry white wine
• 8 cups beef stock
• 2 tsp. minced fresh thyme, or 1 tsp. dried
• 1 bay leaf
• Kosher salt and freshly ground pepper
• 1 crusty baguette
• 2 2/3 cups shredded Gruyère cheese