Step 1

Heat the olive oil in a 6 quart Dutch oven over high heat. Stir in the garlic and cook until just fragrant. Add the onions, season with salt and cook for about 5 minutes, stirring often. Reduce the heat to medium-low and saute' the onions for another 15 to 20 minutes, stirring occasionally until they are a deep amber color.

Step 2

Add the thyme, vinegar and beer. Cook until the liquid is reduced by half, then add the beef stock and bay leaf. Bring to a simmer and continue to cook for 20 more minutes.

Step 3

Meanwhile, preheat the broiler and set out individual oven-proof soup bowls. Discard the bay leaf, then use a ladle to transfer the soup to the individual bowls. Top with toasted bread slices, then 3-4 slices of the cheddar cheese. Broil until the cheese is bubbly and slightly browned. Serve piping hot.

Step 4

Source: Michael Chiarello via The Food Network