Over medium-high heat, melt the butter in a large pot until foaming.

Add the onions, brown sugar, salt and turn the heat to medium. Cook, stirring occasionally, for 30 to 45 minutes until the onions have reduced and caramelized, and they start to brown the bottom of the pot.

While the onions are cooking, preheat the oven to 450 degrees Fahrenheit. Slice 12 half-inch, 45 degree slices of the baguette (enough for 2 slices per serving) and place them on a baking sheet. Toast in the oven for 5 minutes and set aside.

Once the onions have caramelized, add the wine, broth, bay leaves, and thyme to the pot. Bring to a boil over high heat and then reduce the heat to simmer, uncovered, for 30 minutes to concentrate the flavours. Season to taste with salt & pepper.

Remove and discard the bay leaves and thyme sprigs. Ladle the soup into 6 oven-proof bowls. Top each bowl with 2 toasted baguette slices and an equal amount of grated cheese. Broil in the oven until the cheese is melted and golden. Serve immediately.

Makes 6 portions