4cupsbeef broth (or vegetable broth for a vegetarian option)
1teaspoonthyme (dried or fresh)
1leafbay leaf
to tastesalt and pepper
1baguettesliced
1.5cupsshredded Gruyère cheese
for garnishfresh parsley
Instructions
In a large pot or Dutch oven, heat the butter and olive oil over medium heat.
Add the thinly sliced onions, along with the sugar to help with caramelization, and stir to coat in the fats.
Cook the onions, stirring occasionally, for about 30-35 minutes or until they are deeply caramelized and golden brown. Lower the heat if needed to prevent burning.
Once the onions are caramelized, season with salt, pepper, and thyme. Add the bay leaf and pour in the beef or vegetable broth.
Bring the soup to a gentle simmer and let it cook uncovered for 20 minutes, allowing the flavors to meld together.
While the soup simmers, preheat the oven to 400°F (200°C). Arrange the baguette slices on a baking sheet and toast them in the oven for about 5-7 minutes until golden.
After the soup has simmered, remove the bay leaf and taste; adjust seasoning if necessary.
To serve, ladle the soup into oven-safe bowls, place a toasted baguette slice on top of each bowl, and generously sprinkle with Gruyère cheese.
Place the bowls on a baking sheet and broil for 3-5 minutes, or until the cheese is bubbly and golden brown.
Carefully remove from the oven, let cool slightly, and garnish with fresh parsley before serving.
Notes
For a vegetarian option, use vegetable broth instead of beef broth.