Add the butter to a large stock pot or Dutch oven over medium-low heat. Once melted, add the sliced onions and toss to coat in the butter. Cover and cook for 20 minutes, stirring occasionally.

Remove the lid and turn the heat up to medium and cook another 20-25 minutes, or until the onions are caramelized. Stir frequently in this step so the onions don’t burn.

After the onions are deep golden brown, stir in the flour and cook another 30 seconds.

Stir in the beef broth, shredded chicken, white wine, fresh thyme leaves, and Worcestershire sauce. Bring to a boil, then reduce to a simmer and simmer for 5 minutes, or until thickened.

During step 4, preheat oven to a broil. Slice your baguette and place on a baking sheet lined with parchment. Brush the slices with oil, sprinkle with salt, and toast in the oven on broil for 1-2 minutes, until golden. Set aside.

Once the soup is done cooking, transfer to oven-safe ramekins and top with toasted baguette and cheese. Place on a baking sheet and broil in the oven for 2-3 minutes until the cheese is golden brown. Serve!