1. Add butter and onions to large pot over medium heat. Season with a little salt and pepper and cook until sofened.
2. Add sugar and continue to gently stir until onions become golden brown and carmelized, about 25 minutes. Careful to not let them burn, Maintain a medium to medium low heat.
3.Add the flour and cook for 3 more minutes
4.Add beef stock, wine, thyme, celery and bay leaves. Cook partially covered for 30 minnutes.
5.Preheat oven to 350 degrees F.
6.Arrange bread on a baking sheet and brush with melted butter on both side.
7.Bake for 15 minutes, flipping to the other side half way through. Remove from oven and rub a cut clove of garlic onto each piece of bread.
8.Turn over to BROIL.
9. Remove bay leaves and the piece of celery from the soup and ladle soup unto 4 oven proof bowls.
10.Place the toasted bread on top of each bowl. Depending on the size of your bowls you may need two slices of bread.
11.Sprinkle the tops generously with both types of cheese. Broil until the chees is browned and bubbling.