Print
clock clock iconcutlery cutlery iconflag flag iconfolder folder iconinstagram instagram iconpinterest pinterest iconfacebook facebook iconprint print iconsquares squares iconheart heart iconheart solid heart solid icon

Classic French Onion Soup with Gruyère and Baguette Toast Recipe


  • Author: Noah
  • Total Time: 1 hour 30 minutes
  • Yield: 6 servings 1x

Description

A classic French Onion Soup recipe featuring slowly caramelized onions simmered in rich beef broth, topped with cheesy toasted baguette slices for a warming and flavorful meal.


Ingredients

Scale

Soup

  • 100 g / 3.5 oz unsalted butter
  • 1.25 kg / 2.5 lb brown or yellow onions, peeled, halved, thinly sliced top to bottom
  • 3/4 cup (185 ml) dry white wine (optional)
  • 2 tbsp all-purpose flour
  • 1.5 litres / 6 cups / 1.5 quarts good quality beef broth or chicken broth, low sodium/salt reduced
  • 2 dried bay leaves or 3 fresh bay leaves (optional)
  • 3 sprigs fresh thyme (optional)
  • Salt and freshly ground black pepper, to taste

Cheese Toast Topping

  • 68 slices French baguette or other softish bread
  • 100 g / 3.5 oz Gruyere cheese, or mozzarella or other melting cheese of choice
  • Fresh parsley or thyme leaves, for garnish (optional)

Instructions

  1. Caramelize Onions: Melt butter in a heavy-based casserole pot over medium heat until it foams. Add the thinly sliced onions and stir to coat them evenly in the butter.
  2. Cook Onions Low and Slow: Reduce heat to medium-low and cook the onions for 30 minutes, stirring every few minutes until they soften and become semi-transparent.
  3. Salt and Continue Cooking: Increase heat to medium or medium-high and add salt. Cook for another 20 to 30 minutes, stirring frequently, until the onions turn a deep golden brown and develop a sweet flavor.
  4. Deglaze with Wine: Pour in the dry white wine (if using) and simmer rapidly for 2 minutes, stirring to scrape up any browned bits from the bottom of the pot until mostly evaporated.
  5. Add Flour: Sprinkle the flour over the caramelized onions and cook for 1 minute, stirring constantly to combine and cook out the raw flour taste.
  6. Add Broth and Herbs: Pour in the beef or chicken broth. Add the fresh thyme sprigs and bay leaves if using.
  7. Simmer Soup: Cover the pot and lower the heat to maintain a gentle simmer. Let the soup simmer for 30 minutes to develop flavor.
  8. Season Soup: Remove the bay leaves and thyme sprigs. Taste and adjust seasoning with salt and pepper as needed.
  9. Prepare Cheese Toast: Preheat your grill or broiler to high. Toast the slices of bread on each side until they are lightly golden.
  10. Top and Melt Cheese: Place cheese on each toasted bread slice and broil again until cheese melts and bubbles with some browned spots.
  11. Serve: Ladle the hot soup into bowls, top each with 1 or 2 slices of cheesy toast, and garnish with fresh parsley or thyme if desired.

Notes

  • To caramelize onions in a slow cooker: Cook sliced onions with butter on low for 6-8 hours, stirring occasionally, until deep golden and sweet.
  • Dry white wine is optional but adds depth of flavor; it can be omitted or substituted with extra broth.
  • Using low sodium broth controls the saltiness; adjust seasoning at the end.
  • French baguette or other soft bread are preferred for soaking up soup and melting cheese well.
  • Prep Time: 20 minutes
  • Cook Time: 1 hour 10 minutes
  • Category: Soup
  • Method: Stovetop
  • Cuisine: French

Keywords: French Onion Soup, caramelized onions, beef broth soup, cheesy toast soup, classic French soup