Description

French Onion Soup is a classic, rich, and comforting dish known for its deeply caramelized onions simmered in a flavorful broth, topped with toasted baguette slices and melted Gruyere cheese. This recipe guides you through the slow caramelization process, building layers of flavor that culminate in a warm, hearty soup perfect for any occasion.

Ingredients

Scale

Onions

4 large yellow onions (about 5 pounds total)
2 large sweet onions (Vidalia)

Butter and Oils

6 tablespoons butter
3 tablespoons olive oil (optional)

Herbs and Seasonings

2 sprigs fresh thyme
2 bay leaves
Salt and pepper to taste
1 teaspoon Worcestershire sauce

Liquids

¾ cup dry white wine (Chardonnay or Pinot Grigio)
4 cups beef broth (high quality)
1.5 cups chicken broth

Other Ingredients

1 beef bouillon cube or 1 teaspoon Better Than Bouillon
3 tablespoons flour (optional)
1 baguette
6 slices Gruyere cheese

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Instructions

Prepare Onions: Slice the yellow and sweet onions into ¼-inch thick slices using a knife or mandoline slicer for uniformity. This thickness ensures they caramelize properly without becoming too stringy.
Melt Butter: In a large soup pot or Dutch oven, melt the butter over medium-low heat until it begins to foam. This foaming stage indicates the butter is clarified, perfect for coating and cooking the onions smoothly.
Caramelize Onions: Add the sliced onions to the pot and toss with tongs to coat them evenly with the melted butter. Cook them uncovered over medium-low heat, stirring every 10-15 minutes. The onions will slowly caramelize over approximately 2 hours, developing rich brown color and sweetness. Use a splash of white wine and a silicone spatula to deglaze and clean browned bits from the pot bottom periodically.
Add Flour and Wine: When onions are nearly done, sprinkle flour over them and cook for 2 minutes to eliminate raw flour taste and help thicken the soup. Then add the remaining white wine, increase heat to medium-high, and toss frequently until the onions are deeply browned and fragrant.
Combine Broths and Herbs: Stir in beef broth, chicken broth, beef bouillon cube (or bouillon paste), Worcestershire sauce, bay leaves, and fresh thyme sprigs. Bring the soup to a simmer on medium heat with the lid cracked, and let it cook gently for 45 minutes to meld the flavors.
Prepare Baguette: Meanwhile, preheat your oven to 350° F (175° C). Slice the baguette into ½ inch thick pieces, brush the tops with olive oil if using, and bake them for about 5 minutes until lightly toasted.
Melt Cheese on Toast: Increase the oven temperature to 450° F (230° C). Place a slice of Gruyere cheese on top of each toast slice and bake until the cheese melts, bubbles, and turns golden brown.
Finish Soup: Remove the bay leaves and thyme stems from the soup. Season with salt and pepper to taste. Ladle the hot soup into bowls and top each serving with a cheesy toasted baguette. Serve immediately for best flavor and texture.

Notes

Use approximately 5 pounds of onions total to achieve the right volume and flavor intensity.
If you prefer not to use wine, substitute with 3 tablespoons white wine vinegar plus additional chicken or beef broth to total ¾ cup liquid.
Other excellent cheese alternatives to Gruyere include Comté, Emmental (Swiss), or Provolone for varied flavor profiles.
Crock Pot Method: Caramelize onions in the slow cooker on low for 10 hours with butter, then finish cooking with flour, wine, broths, and seasonings on the stovetop or back in the slow cooker for additional cooking time.
An Instant Pot version is available for a quicker pressure-cooked alternative.

Nutrition

Serving Size: 1 bowl with toast
Calories: 340 kcal
Sugar: 10 g
Sodium: 900 mg
Fat: 20 g
Saturated Fat: 12 g
Unsaturated Fat: 7 g
Trans Fat: 0.3 g
Carbohydrates: 28 g
Fiber: 3 g
Protein: 12 g
Cholesterol: 45 mg