How to make it:
Start by cutting both the top and root end off of the onions. Peel the skin off. Now, following the lines of the onion, cut through the middle: top to root. Then, flip to the flat side and cut parallel down the lines again, slicing about 1/2" thick pieces. Be sure not to slice too thin; you want to feel the bite of the onion vs them being stringy.

In a large soup pot, sauté the onions with the butter and a pinch of salt on medium-high heat for 10 minutes, stirring every 3-4 minutes. Turn the heat to medium-low and let cook down for another 10 minutes. The onions will turn a rich golden brown color.

When they're golden brown and soft, add in the minced garlic. Stir and sauté for 30 seconds.

Deglaze the pan with the wine. Bring to a boil on medium-high heat, then reduce the heat to medium-low and simmer until the wine has evaporated and the onions are jammy, about 10 minutes.

Dust the onions with the flour and give them a stir. Keep the heat at medium-low, and cook for about 5 minutes to cook out the raw flour taste. Stir occasionally to keep the flour from burning. This will help thicken the broth and achieve a rich texture.

Now add the beef broth and the bay leaf. Bring the soup back to a simmer on medium heat, and cook for more 20 minutes. Season, to taste, with salt and pepper. Discard the bay leaf.

When you're ready to eat, preheat the oven to 400°F. Slice the French bread loaf into 1/2" thick pieces. Arrange onto a baking sheet and lightly spray with cooking oil on both sides. Bake until lightly golden brown, about 5-8 minutes - but watch carefully. You can choose to add the cheese to the bread here, but still toast it prior, otherwise it won't get crispy. Just add the cheese, then pop back in the oven to melt.

Ladle the soup into soup crocks. Place the soup crock on a baking sheet.

First, add a hefty pinch of shredded gruyere directly to the soup. This will add a cheesy texture inside the soup. Then, add the toast on top of the soup, covering all of the surface area. Feel free to stack a few on there if they're small pieces. Layer on a provolone slice, then sprinkle with shredded Gruyere and parmesan. Broil on the middle rack just until the cheese is melty, about 2 minutes.

Use the rest of the toast for dipping.

If you don't have soup crocks, ladle the soup into a bowl. Toast the cheese bread on the baking sheet, then place on top of the soup.

Sprinkle with fresh parsley for garnish.