In a large heavy stockpot, melt butter over medium-high heat

Add the sliced onion and cook over medium heat for about 30 minutes, stirring every 3-5 minutes until the onions are caramelized but not burned.

Add in the garlic and flour and cook for 1-2 minutes.

Pour in the white wine and deglaze the pan. Use the back of a spoon to scrape up any browned bits from the bottom of the pan.

Add in Worcestershire, bay leaf,salt, pepper and broth.

Stir to combine and bring the mixture to a boil.

Once boiling, reduce heat to medium-low, cover, and simmer for 10-15 minutes.

Remove the bay leaf.

While the soup is simmering, toast the bread. Preheat the oven to 400 degrees F and slice the baguette into 1 inch slices.

Lay out in a single layer on a baking sheet. Bake for 5-6 minutes until toasted and golden brown around the edges.

Switch the oven to broil.

Ladle the soup into oven safe bowls. (If you don't have oven-safe bowls, see notes for more tips.)

Top with 1-2 toasted baguettes, and place the gruyere cheese on top of the baguettes. Broil for 2-4 until the cheese is melted.

Remove from the oven and serve immediately while the soup is still hot. Enjoy!