This authentic French onion soup, topped with melted Gruyere cheese and homemade croutons, is the epitome of a cozy comfort dish.

2 bowls onion soup

We love this French Onion Soup recipe, made with caramelized onions, wine and beef broth. Top it off with homemade croutons and lots of melted cheese—it’s so good. And guess what the French onion soup secret ingredient is? Fish sauce! Keep reading :)

What is French onion soup?

This classic French soup recipe is made of onions, beef stock, and wine. It’s often served with bread on top, covered with melted cheese.

bowls of onion soup

Why we love this soup

Jammy, buttery onions are brightened with red wine and melted into rich, herby beef bone broth in this dish. Then it’s topped with more stringy, melty cheese. It’s a soup that you dream of on a cozy fall day; it’s the soup that people will try, and then beg you for the recipe. It’s a soup that I’ve eaten with soft scrambled eggs, and we call it a “French onion soup omelette.”

Bottom line, it is a must-make soup that everyone loves!

how to make french onion soup

Ingredients for French Onion Soup:

Yes, French onion soup is a bit labor intensive. It’s also one of the simplest, yet most flavorful, soups around. There is fish sauce added to the onions, but this does not make the soup taste like fish (just like anchovies in a Caesar salad dressing don’t make the dressing taste like fish). It simply adds depth of flavor to the broth. What are the best onions for french onion soup? Regular yellow onions!

  • Yellow onions
  • Butter
  • Sugar
  • Salt + black pepper
  • Red wine
  • Beef stock
  • Fish sauce
  • Bay leaves
  • Fresh thyme
  • Artisan bread loaf
  • Olive oil
  • Shredded Gruyere cheese (substitute or add Swiss, coastal cheddar, gouda, and/or Parmesan)

cheesy french onion soup

How do you make the soup?

The key to great onion soup is to cook the onions until they are completely caramelized: sweet, soft and dark golden brown.

Make the croutons:

  1. If you’re using fresh bread, cut the loaf into cubes and arrange in a single layer on a rimmed baking sheet. Bake until dried out and hardened.
  2. To toast the bread cubes, set the broiler to high, toss the cubes in the olive oil or butter, and sprinkle with salt. Place the baking sheet back into the oven 2 racks below the broiler, and toast and toss 2-3 times in between until all sides are golden.
  3. Remove from the oven and let sit until ready to use.

cheesy bite of french onion soup

Make the soup:

  1. In a large pot or Dutch oven, melt the butter over medium-high heat. Add the onions and season with sugar and salt. Toss in the butter, then top with a lid and let sit for stirring 1-2 times.
  2. Once the onions have sweated and are softened, remove the lid. Stir semi-frequently, as the onions reduce. If you notice the onions are starting to burn, lower the heat as needed and add splashes of water to prevent burning.
  3. Note: As the onions get closer to being done, golden, sticky fond will start to form on the bottom of the pan. Simply scrape it up with a spatula, or add water, one teaspoon at a time, to prevent it from burning.
  4. After cooking, lower the heat to medium low. By this point the onions should be significantly reduced, golden and jammy. Add in the red wine and scrape up any fond from the bottom of the pan. Reduce the wine and add the beef stock, fish sauce, black pepper, bay leaves, and thyme. Bring to a boil, then reduce the heat and simmer more.
  5. Portion out the soup into ramekins arranged on a parchment-lined baking sheet. Top each portion with about 1/2 cup of cheese followed by a layer of croutons, and another 1/2 cup of cheese. Place in the oven, 3 racks below the broiler, set to high. Broil until melted and golden.
  6. Let soup chill a few minutes before garnishing with fresh chives and serving warm.

onion soup with croutons

How to cook the onions:

Onions get slowly cooked until sweet and caramelized, then simmered in rich broth until they’re practically falling apart.

Tips and substitutions:

  1. Make ahead: The onion soup can be refrigerated for up to two days. Reheat gently before topping with croutons and cheese.
  2. We recommend using a higher quality beef bone broth in this recipe, because it really does add great depth of flavor and additional nutrients to the final product.
  3. Also use a higher quality wine, something medium bodied and not too sweet like a Cabernet Sauvignon or a Merlot. Make sure it’s something you’d drink (not just a cheap red).
  4. Go to a local bakery and buy a crusty, rustic loaf to make the croutons. If there is any time to support a local business and buy some extra flavorful bread, I think it should be for this recipe.

french onion soup with croutons

This is the best French onion soup. It’s warm, savory, sweet, cheesy, and the absolute perfect meal for a cold winter night.

Oh, and when you read the recipe, you may want to know what “fond” is? “Fond” refers to the caramelized bits left in the bottom of a pan after you’ve browned meat or vegetables. It’s the browned, flavorful bits that taaste so good!

ENJOY!

More delicious winter soup recipes you may like:

Pear Potato Soup

Italian Sausage Tortellini Soup

Chicken Meatball Italian Wedding Soup

Caramelized Apple Onion Soup

croutson on onion soup
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Get the Recipe:

BEST French Onion Soup

Prep Time: 20 mins
Cook Time: 1 hr 45 mins
Total Time: 2 hrs 5 mins
Yield: 6

Ingredients
 

  • Ingredients:
  • 3½-4 lb yellow onions, about 4-5 large onions
  • 5 Tbsp butter
  • 1 tsp sugar
  • Salt to season
  • 1 ½ c dry red wine
  • 6 c beef stock
  • 1 Tbsp fish sauce
  • 1 tsp fresh cracked black pepper
  • 2 bay leaves
  • 3-5 sprigs fresh thyme
  • 1 crusty, artisan bread loaf, cut into 1’’ cubes (or bite size pieces), preferably very stale (about 6 cups total)
  • 5 Tbsp olive oil or melted butter
  • 6 c shredded Gruyere cheese, substitute or add Swiss, coastal cheddar, gouda, and/ or Parmesan

Instructions
 

Make the croutons:

  • If you’re using fresh bread, cut the loaf into cubes and arrange in a single layer on a rimmed baking sheet. Add to an oven set to 250 degrees and bake until dried out and hardened, 15-20 minutes.
  • To toast the bread cubes, set the broiler to high, toss the cubes in the olive oil or butter, and sprinkle with salt. Place the baking sheet back into the oven 2 racks below the broiler, and toast for 4-6 minutes (depending on the broiler) tossing 2-3 times in between until all sides are golden.
  • Remove from the oven and let sit until ready to use.

Make the soup:

  • In a large pot or Dutch oven, melt the butter over medium-high heat. Add the onions and season with sugar and salt. Toss in the butter, then top with a lid and let sit for 12-15 minutes, stirring 1-2 times.
  • Once the onions have sweated and are softened, remove the lid. Stir semi-frequently, as the onions reduce for 35-45 minutes. If you notice the onions are starting to burn, lower the heat as needed and add splashes of water to prevent burning.
  • Note: As the onions get closer to being done, golden, sticky fond will start to form on the bottom of the pan. Simply scrape it up with a spatula, or add water, one teaspoon at a time, to prevent it from burning.
  • After 35-45 minutes, lower the heat to medium low. By this point the onions should be significantly reduced, golden and jammy. Add in the red wine and scrape up any fond from the bottom of the pan. Reduce the wine for 5 minutes, then add the beef stock, fish sauce, black pepper, bay leaves, and thyme.
  • Bring to a boil, then reduce the heat and simmer for 30-45 minutes.
  • Portion out the soup into ramekins arranged on a parchment-lined baking sheet. Top each portion with about 1/2 cup of cheese followed by a layer of croutons, and another 1/2 cup of cheese. Place in the oven, 3 racks below the broiler, set to high. Broil until melted and golden—5-8 minutes depending on the broiler.
  • Let soup chill a few minutes before garnishing with fresh chives and serving warm.

Notes

Croutons: Often, French onion soup is made with crostini like croutons (stale, toasted bread slices), but I prefer to use bread cubes, because they are friendlier to eat with a spoon, given that they require not cutting or breaking like sliced bread.
You can bake fresh bread cubes in the oven as instructed below, or, you can let them sit out uncovered on a baking sheet for 1-4 days until very dry and stale.
I prefer having very dry cubes, because, after toasting with butter and salt, they absorb the broth like sponges and still manage to have a bit of crunch in the center, which I love because it adds textural contrast to the jammy soup.
Cuisine: American
Course: Soup
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french onion soup