Step 1

Melt the butter in a 2-quart saucepan over medium heat. Add the onions, garlic, thyme, salt and pepper and cook until the onions are very soft and caramelized, about 25 minutes.

Step 2

Add the wine, bring to a boil, reduce the heat and simmer until the wine has evaporated, about 5 minutes.

Step 3

Sprinkle the flour over the onions and stir. Reduce the heat to medium-low and cook for 10 minutes, stirring occasionally so that the flour doesn't burn.

Step 4

Stir in the chicken broth and bring the soup back to a simmer, cook for 10 minutes.

Step 5

Taste and add additional salt, if necessary.

Step 6

Heat the broiler. Place the slice of French bread on a baking sheet. Sprinkle the Gruyere cheese over the top and broil until bubbly and golden brown, 3-4 minutes.

Step 7

Place the bread in a soup bowl and pour the soup over the top.