• In a large pot over medium heat, melt the butter. Add onions, garlic, thyme, bay leaf, salt, and pepper. Cook for about 20-25 minutes or until onions become very soft and caramelized.
• Add the white wine and bring to a boil. Scrape any browned bits from the bottom of the pan and allow the mixture to simmer for about 5-10 minutes or until the wine has evaporated.
• Remove the bay leaf and thyme sprigs. 
• Add in the flour, stir to coat the onions. Reduce the heat to medium-low and cook for about 10 minutes. 
• Stir in the beef broth and bring the soup back to a simmer. Simmer for about 10 minutes, allowing the soup to thicken slightly. 
• While the soup is simmering, preheat the oven to 450°F. and line a baking sheet with parchment paper. 
• Coat both sides of the French bread slices with olive oil. Place onto the prepared baking sheet and toast in the oven for about 5-6 minutes.
• Remove the baking sheet from the oven and flip the toasts over and top with Gruyere cheese. 
• Return the baking sheet to the oven and bake until cheese has melted and is slightly golden brown.
• Spoon the soup into a bowl and top with cheesy toast.
• Serve immediately. Store any leftovers in the refrigerator.

Alternatively

• If you desire, you can …
• Fill oven-safe bowls with the soup and top with french bread and cheese. 
• Broil it all in the oven for about 10 minutes, or until the cheese is melted and slightly golden brown.