Slow-cooked onions are cooked to perfection, then simmered in broth and spice, and topped with toasted crostini and rich melty cheese!

Course: Soup

Cuisine: French

Prep Time: 10minutes 

Cook Time: 1hour  30minutes 

Total Time: 1hour  40minutes 

Servings: 4 servings

Calories: 258kcal

Author: Beth Pierce


  • 1 tablespoon unsalted butter
  • 1 tablespoon olive oil
  • 4 large yellow onions sliced in half and cut from pole to pole in no greater than 1/4 inch slices
  • 2 cloves garlic minced
  • 1 teaspoon dried thyme
  • 1/2 cup dry white or red wine see notes
  • 3 cups low sodium beef broth or beef stock
  • 1 cup low sodium chicken broth
  • 2 teaspoons Worcestershire Sauce
  • 1 bay leaf
  • kosher salt and freshly ground pepper to taste
  • Crostinis or large croutons
  • 1 cup shredded Gruyère or Swiss cheese


  • Heat butter and olive oil in a Dutch Oven or stock pot over medium to medium/low heat.  Add the onions and cook for about 45 minutes stirring every few minutes until a rich golden brown.
  • Add the garlic and thyme. Cook for 1 minute. Add the wine, and using a spoon or spatula, try to remove as much of the brown glazing from the bottom of the pan as possible. Allow the wine to simmer with the onions for about 5 minutes.
  • Add the chicken broth, beef broth, Worcestershire Sauce, and bay leaf. Simmer for 20 minutes.  Discard the bay leaf and season with kosher salt and fresh ground black pepper to taste.
  • Add the soup to oven-safe bowls or cups. Top with crostini and grated cheese. Slip under the broiler for 2-3 minutes.


  • Caramelized onions are the star of this show, so don’t cut the process short.
  • Either dry red wine or dry white wine can be used. Red adds a more robust flavor, and white is more subtle. If you have a personal preference on which one you prefer to drink, go with that.
  • You can use all beef broth for a richer, fuller flavor or if it is just more convenient. I always have beef and chicken broth in the house, so a combination is usually the way I go on this recipe.
  • I find Crostini works best for this recipe. They hold up long enough to provide structure and texture without coming off as a soggy piece of bread. Or simply toast or broil baguette slices until golden brown. 
  • Gruyere is a smooth melting type of Swiss Cheese with fewer and smaller eyes. If it is not available, you can substitute Swiss or Jarlsberg.
  • Broilers are very unpredictable. Stay close by and monitor well.
  • Store leftover soup in an airtight container in the refrigerator. It is best to wait to add the crostini and cheese until you reheat.


Calories: 258kcal | Carbohydrates: 16g | Protein: 11g | Fat: 15g | Saturated Fat: 7g | Polyunsaturated Fat: 1g | Monounsaturated Fat: 5g | Trans Fat: 0.1g | Cholesterol: 33mg | Sodium: 113mg | Potassium: 302mg | Fiber: 3g | Sugar: 6g | Vitamin A: 328IU | Vitamin C: 9mg | Calcium: 282mg | Iron: 1mg


No comments yet. Why don’t you start the discussion?

Leave a Reply

Your email address will not be published. Required fields are marked *