Ingredients
For the Soup
- 1 tablespoon olive oil
- 2 tablespoons butter
- 5 large yellow onions, thinly sliced
- 1 teaspoon salt, plus more to taste
- 2 tablespoons all-purpose flour (or gluten-free flour)
- 3 cloves garlic, finely minced
- 1/2 cup dry white wine (or beef broth), for deglazing
- 7–8 cups beef broth (or bone broth; can mix with chicken broth if desired)
- 1 teaspoon fresh thyme
- Freshly ground black pepper, to taste
- 1 tablespoon Worcestershire sauce
- 1 bay leaf
For the Baguettes
- 1 demi French baguette, cut into 1-inch thick slices
- 1 tablespoon butter
- Garlic powder, for sprinkling
- 8 ounces Gruyère cheese, thickly shredded
Instructions
- Caramelize the Onions: Melt the olive oil and butter in a large Dutch oven or pot over medium heat. Add the sliced onions and 1 teaspoon salt, stirring to coat. Cook, stirring occasionally, for 30-40 minutes until the onions are a deep golden brown and caramelized. Reduce the heat if they brown too quickly or start to stick.
- Add Flour and Garlic: Once caramelized, sprinkle the flour and minced garlic over the onions. Stir well to coat and cook for 2 more minutes to remove the raw flour taste.
- Deglaze and Simmer: Pour in the dry white wine or beef broth to deglaze the pan, scraping up all the browned bits from the bottom. Gradually add the beef broth, thyme, black pepper, Worcestershire sauce, and bay leaf. Bring to a simmer and cook uncovered for 30 minutes, letting the flavors meld.
- Season and Finish Soup: Remove the bay leaf. Taste the soup and adjust seasonings, adding more salt or pepper as needed.
- Toast the Baguette: About 10 minutes before the soup is done, preheat the oven to 400°F (200°C) and line a large baking sheet with parchment. Arrange the baguette slices in a single layer, brush with melted butter, and sprinkle with garlic powder. Toast for 5 minutes per side until golden and crisp.
- Prepare Cheese-topped Toast: Option 1: Sprinkle shredded Gruyère over the toasted baguette slices. Bake an additional 3-5 minutes until cheese is melted. Serve the soup in bowls topped with a cheesy baguette slice. Option 2: For a traditional touch, ladle the soup into oven-safe bowls or crocks set on a baking sheet. Top each with a toast slice and about 1/3 cup Gruyère. Broil until the cheese is melted and bubbling, 2 minutes (watch carefully!). Serve immediately.
Notes
- You can substitute some or all of the beef broth with chicken broth for a slightly lighter flavor.
- Use gluten-free flour and baguette to make the soup gluten-free.
- Watch your onions closely while caramelizing to avoid burning.
- This soup freezes well; check the full post for reheating instructions.
- Gruyère is traditional, but Swiss or mozzarella cheese can be substituted.
- Prep Time: 15 minutes
- Cook Time: 1 hour
- Category: Main-course
- Method: Stovetop
- Cuisine: French
- Diet: Vegetarian
Nutrition
- Serving Size: 1 serving
- Calories: 347
- Sugar: 5.9g
- Fat: 21.2g
- Saturated Fat: 11.4g
- Carbohydrates: 22.3g
- Fiber: 2.3g
- Protein: 17.8g
