Best French Onion Soup

In a large Dutch oven, heat the olive oil, stir in the onions and salt, cover, and cook 30 minutes, stirring every 5 minutes. 2. Add the white wine and saute an additional 15 minutes until the wine is absorbed and the onions are soft and brown. 3. Add the flour, thyme, bay leaves, and garlic; stir and cook over low heat about 2 minutes. 4. Add the red wine and cook briefly, about 1 minute. 5. Add the beef broth, whisking vigorously, bring to a boil, reduce to a simmer, and simmer partially covered 25 minutes, stirring occasionally; remove the thyme stems and bay leaves and season with salt and pepper. 6. Toast the baguette slices at 375 F until crisp, about 3 minutes. 7. Preheat the broiler on low, ladle the soup into oven-proof bowls, top with toasted baguette and cheese, and broil until melted and browned, about 2 minutes. 8. Serve immediately.