Instructions

1. Caramelize the onions: Melt butter and olive oil in a large pot over medium heat. Add onions and cook, stirring occasionally, for 35–45 minutes until deeply golden and caramelized.
2. Add garlic and cook for 1 minute until fragrant.
3. Sprinkle flour over the onions and stir for 1 minute.
4. If using wine, pour it in and simmer for 2 minutes, scraping up any browned bits.
5. Add beef broth, Worcestershire sauce, bay leaf, thyme, salt, and pepper.
6. Bring to a simmer and cook for 20–25 minutes.
7. Prepare the bread: Toast baguette slices until lightly crisp.
8. Ladle soup into oven-safe bowls and top each with toasted bread and shredded Gruyère cheese.
9. Broil: Place bowls under the broiler for 2–3 minutes until the cheese is melted and bubbly.
10. Serve immediately while hot.