Step 1

Heat a large pot or dutch oven over high heat. Melt the butter, then add olive oil, brown sugar, and salt, stir to combine.

Step 2

Add in the onions and stir to coat, saute, and frequently stir until onions begin to soften and lightly brown, about 5 minutes. Reduce heat to medium, cook onions, frequently stirring, until evenly browned, about 20 to 25  minutes.

Step 3

Once the onions finish caramelizing, add the garlic and saute until fragrant, about 30 seconds. Add the wine to deglaze the pan, stir to scrape any browned bits on the bottom. Increase heat to high, allow the wine to boil and evaporate, frequently stirring, about 4 to 5 minutes.

Step 4

Add the beef stock, thyme sprigs, and bay leaf. Bring stock to a boil, cover, and reduce to a simmer over low heat, about 30 minutes.

Step 5

Discard thyme sprigs and bay leaf. Season the soup with salt and pepper to taste.

Step 6

Place the sliced bread on a baking pan in the center of the oven. Broil on until golden brown, about 3 to 5 minutes per side.

Step 7

Add soup to four 12-ounce bowls, top with toasted bread slices (1 to 2), and evenly distribute the cheese on top of each piece. Alternatively, you can use two larger 24-ounce bowls for more significant portions. Place the bowls on top of a sheet pan.

Step 8

Broil on high, about 8 inches away from the oven’s top until the cheese melts and turns golden brown, about 5 to 6 minutes. Garnish the soup with black pepper and chopped thyme. Serve immediately while still hot and bread is crunchy.