Step 1

Slice the onions into ¼-inch slices, (no thinner). They'll reduce in size quite a bit and you don’t want them to be too stringy. (Using a mandoline slicer makes this much easier).

Step 2

Melt the butter in a large soup pot or dutch oven over medium-low heat. Wait until it begins to foam, this allows water to evaporate out, leaving the butter more clarified and smooth.

Step 3

Add the onions and use tongs to toss and coat them in the butter. Leave them uncovered as they cook.

Step 4

The onions will caramelize slowly, up to 2 hours or longer. Stir them every 10-15 minutes. As the onions caramelize, they may leave some brown residue at the bottom of the pot. Add a splash of wine and use a silicone spatula to 'clean' the bottom of the pot. Repeat as needed throughout the cooking process

Step 5

When the onions are nearly done, sprinkle flour over them and cook for 2 minutes. Add any remaining wine and increase the heat to medium-high. Toss the onions more frequently. They are done when they are richly brown and sweet.

Step 6

Add the beef broth, beef bouillon, chicken broth, Worcestershire sauce, bay leaves and thyme. Simmer over medium heat for 45 minutes with the lid cracked.

Step 7

While the soup simmers, preheat the oven to 350° F.

Step 8

Slice the baguette into ½ inch thick slices. Brush the tops with olive oil and bake for about 5 minutes.

Step 9

Increase the oven temperature to 450° F. Top each baguette with cheese and bake in the oven until the cheese melts and begins to bubble and brown.

Step 10

Remove the bay leaves and thyme stems. Season to taste with salt and pepper.

Step 11

Ladle the warm soup into each bowl and top each of them with the warm baguettes. Serve!