In a large pot, melt butter over medium heat. Add the onions, stir well, cover and cook for 5 minutes. Uncover the pot, reduce heat to medium-low and continue to sauté, stirring occasionally, until onions are tender and golden brown, about 25 -30 minutes.
Increase heat to medium-high. Sprinkle the flour over the onions and stir until combined. Add the wine, beef broth, thyme, bay leaf and Worcestershire sauce. Taste and add more salt and/or pepper if you like. At first boil, reduce heat to medium-low and simmer, uncovered about 30 minutes. Taste and adjust the seasoning if necessary. Remove bay leaf and discard.
Place rack of your oven in the center and turn the broil on.
Distributed the soup into individual bowls, place 1-2 slices of bread over the soup and sprinkle with plenty of Gruyere cheese.
Bake until cheese is melted and bubbling, about 2-3 minutes.
If you want you can toast the bread before you put in the soup to give a crisper consistency.
Classic Onion Soup
Amount Per Serving
Calories 244Calories from Fat 144
% Daily Value*
Saturated Fat 10g50%
Vitamin A 510IU10%
Vitamin C 5mg6%
* Percent Daily Values are based on a 2000 calorie diet.