Melt the butter in a large soup pot over a medium-high heat. Add the shallots, garlic and brown sugar. Cook for about 20-25 minutes, stirring frequently, until softened, deep golden in colour and caramelized. Add the thyme and sage and continue cooking for another 3-5 minutes.
Reduce the heat to low and add the flour to the pan. Stir for 1-2 minutes. Add the wine, stock, Worcestershire sauce, and bay leaves. Increase the heat to medium-high and return the soup to a simmer for 10 minutes. Remove and discard the bay leaves. Season to taste with salt and pepper.
Preheat the grill to high.
Ladle the soup into oven safe bowls. Add a slice of bread to each and top evenly with each cheese. Place each soup bowl on a baking sheet and transfer to the oven, grill until bubbly and golden brown, 3 to 5 minutes.
Alternatively, grill the bread topped with the cheese on a baking tray and remove once golden. Place a slice on top of each bowl of soup.