Ingredients
Scale
- 4 large yellow onions, sliced
- 3 tbsp unsalted butter
- 1 tbsp olive oil
- 4 cups beef or vegetable broth
- 1/2 cup dry white wine (optional)
- 1 tsp sugar
- Salt and black pepper to taste
- 1 baguette, sliced
- 2 cups grated Gruyere cheese
Instructions
- Heat butter and olive oil in a large pot over medium heat. Add sliced onions and cook slowly, stirring frequently, until caramelized (about 30-40 minutes).
- Stir in sugar, salt, and pepper. Cook for another 5 minutes.
- Add wine (if using) and cook until reduced by half.
- Pour in broth and bring to a simmer. Taste and adjust seasoning.
- Preheat oven to 400°F (200°C). Place baguette slices on a baking sheet and toast until golden.
- Ladle hot soup into oven-safe bowls, top with toasted baguette slices, and sprinkle with Gruyere cheese.
- Bake until cheese is melted and bubbly, about 10 minutes. Serve hot, garnished with thyme if desired.
Notes
- Caramelizing onions slowly is key to developing the rich flavor of the soup.
- You can substitute beef broth with vegetable broth for a vegetarian version.
- Broil the cheese-topped bread for a couple of minutes for extra crispness.
- Prep Time: 15 minutes
- Cook Time: 45 minutes
- Method: Sauté, simmer, bake
- Cuisine: French
- Diet: Vegetarian
Nutrition
- Serving Size: 1 bowl
- Calories: 380 Kcal
- Sugar: 8g
- Sodium: 980mg
- Fat: 18g
- Saturated Fat: 10g
- Unsaturated Fat: 6g
- Trans Fat: 0g
- Carbohydrates: 45g
- Fiber: 4g
- Protein: 15g
- Cholesterol: 55mg