Instructions:
- Caramelize Onions: Heat olive oil and butter in a pot over medium heat. Add onions and cook, stirring occasionally, for 10 minutes. Sprinkle with sugar and cook uncovered, stirring occasionally, for 30-40 minutes until caramelized and browned. Add garlic and cook for 1 more minute.
- Deglaze and Simmer: Add sherry, scraping the pot to deglaze. Stir until sherry is evaporated (3 minutes). Add beef stock, bay leaf, thyme, and 1 tsp salt. Simmer partially covered for 30 minutes. Adjust seasoning with remaining salt and pepper.
- Prepare Croutons: Preheat oven to 400°F. Slice baguette and brush with olive oil. Bake for 6-8 minutes until golden brown.
- Assemble and Broil: Top baguette slices with half the cheese and broil for 2-3 minutes until melted and golden.
- Serve: Pour soup into bowls, sprinkle with remaining cheese, and top with cheesy toasts.
Enjoy!