Instructions

1. Peel and thinly slice the onions.
   
2. Melt the butter in a saucepan over medium heat.
   
3. Add the onions and a pinch of sugar. Sauté over low heat, stirring regularly to prevent burning, until softened and lightly caramelized.
   
4. Pour half of the broth into the saucepan and let it reduce almost completely over medium heat, stirring occasionally.
   
5. Meanwhile, wash and dry the thyme, and pluck the leaves.
   
6. Pour the remaining broth into the saucepan, add the thyme leaves (reserve a few for garnish), and stir. Cook over medium heat, stirring occasionally.
   
7. Meanwhile, slice and toast the baguette.
   
8. When the soup has reached the desired consistency, preheat the oven to 200°C/400°F (180°C/350°F for a convection oven). Transfer the soup to oven-safe ramekins, sprinkle with grated cheese, place baguette slices on top, and sprinkle with more cheese.
   
9. Bake the soup until the cheese is melted (10-15 minutes, or 8-12 minutes in a convection oven), but not browned. Serve the soup garnished with the reserved thyme.