Perfectly caramelized onions, a rich beef broth, and cheesy toast, makes this classic French onion soup a go-to when you need a little comfort food! It’s a hearty soup recipe too good to miss!
I love French onion soup.
How could you not?
There’s onions that have been cooked down so they are sweet and delicious, crusty bread on top (soaking all that beefy broth) and copious amounts of melty cheese.
This winter soup is definitely a meal in itself. With a nice glass of red wine, you’re set!
You will use quite a bit of onions in the recipe, but they quickly cook down and, besides that, this is French onion soup, isn’t it?
And, fair warning, your breath may not thank me after eating this soup, but your belly surely will! It’s worth it, though!
What Is French Onion Soup?
Essentially, French onion soup is a big bowl of comfort food, which includes caramelized onions and beef broth with a piece of melty, cheesy bread on top.
For this onion soup, you’re gonna need:
- Onions (of course, like red, white, or yellow (or a combo of those))
- Olive oil & butter
- Seasonings, like salt, pepper, and thyme
- Flour (to thicken things a little)
- Beef broth
- Worcestershire sauce
- Balsamic vinegar
It’s amazing how some humble ingredients, like onions, along with a few other things can and be transformed into something so special!
How To Make It
Full details in recipe card below, but here are the basics:
Make the Onion Soup
- Caramelize onions (easy step-by-step instructions to caramelize onions here).
- Stir in some garlic and cook until fragrant.
- Deglaze with a little wine, scraping up those little brown bits on the bottom of the pot with a wooden spoon.
- Stir in flour (this will help thicken things), then season with thyme, salt and pepper.
- Pour in beef broth, Worcestershire sauce and balsamic vinegar. Stir and cook for a little while.
Assemble the Soup
- Lay French onion soup bowls onto a sheet pan and portion soup into them.
- Top soup with bread (you can drizzle or brush with a little avocado oil if you like).
- Pile on shredded Gruyere cheese.
- Bake until the cheese melts.
Do I Have to Use Special French Onion Soup Bowls?
Nope! Not at all.
You do, though, have to use oven-safe bowls when baking the cheesy toast!
Tip: Don’t have oven-safe bowls? Skip putting bowls in the oven. Bake the cheesy toast separately and place on the hot soup after.
What Can I Use Instead of Gruyere Cheese?
I love Gruyere here because it’s tasty, rich, and melts well.
However, if you don’t have Gruyere cheese on hand (or simply rather use another variety), try plain Swiss cheese or Fontina.
How To Thicken Soup
You can thicken French onion soup broth in various ways:
- Flour: Flour was used in this recipe. Sprinkle over top when onions are cooked.
- Cornstarch slurry: To make a cornstarch slurry, you’ll need equal parts cornstarch and water. Mix together 1 tablespoon each of cornstarch and cold water and stir into the soup. Then bring the soup to a simmer and cook until thickened, about 2 minutes. You can add another tablespoon each of cornstarch and cold water if you want a thicker consistency.
- Reducing the soup on a low simmer: Simmer until you’ve reached your desired consistency.
- Adding more caramelized onions: More onions means a denser consistency!
- Use soup to thicken: Remove about a cup of soup from the pot, place into a heat-safe container and blend with an immersion blender until smooth. Then, stir back into the pot.
Tips for Making This Recipe
- This soup is super simple, but does take time (especially because there are caramelized onions involved). Just have some patience and it will be well worth it!
- Like with any soup, use a good-quality broth. Homemade beef broth would be awesome; if you don’t have that, store-bought is perfectly fine.
- If you want to bake the cheesy toast in the oven on top of the soup, don’t fill your bowls to the brim. Once you add the bread, it will displace some of the liquid.
- Use a hearty bread that can hold up to the broth. I like focaccia or ciabatta (or something similar). Of course, no matter what you put on there it will absorb some liquid (which is awesome), but you don’t want to use a basic white bread here.
- Use a sheet pan to make things easier for putting those bowls in the oven and taking them out. Plus, the sheet pan will catch any spills, meaning less cleanup.
More Caramelized Onion Recipes
If you make this French onion soup recipe, please leave a comment below!
This recipe was originally published in September 2015 but has been updated.
French Onion Soup
- 2 tablespoons butter
- 2 tablespoons olive oil
- 3 pounds yellow onions, peeled and sliced about ⅛-inch to ¼-inch thick
- 2 cloves garlic, minced
- ⅓ cup white wine, or beef broth
- 1 teaspoon dried thyme, or 1 tablespoon chopped fresh thyme leaves
- ¾ teaspoon salt
- ½ teaspoon freshly ground black pepper
- 2 tablespoons all-purpose flour
- 6.5 cups low sodium beef broth
- 1 tablespoon Worcestershire sauce
- 1 teaspoon balsamic vinegar
- 6 slices bread, use your favourite bread
- 1 tablespoon avocado oil, optional
- 1.5 to 2 cups shredded Gruyere cheese, depending on how much cheese you want
- Chopped fresh thyme leaves, garnish to taste (optional)
- Add butter and olive oil to a large pot or Dutch oven over medium-low heat. When butter is melted, add ⅓ of the onions. Stir to coat in butter and oil and cook for 5 minutes, stirring periodically.
- After 5 minutes, add another ⅓ of the onions, stir and cook for 5 minutes more. Continue with remaining ⅓ of onions. Note: Because we are caramelizing a lot of onions here, I like to add in batches rather than all at once.
- Cook for about 45 minutes in total, checking on every 5 minutes or so, ensuring they aren't burning and using a wooden spoon to scrape up any brown bits on the bottom of the pot to incorporate them into the onions. Every once in a while, add a splash of hot water to loosen any excessive brown bits and encourage the onions to cook, no more than ¼ cup at a time (up to about 1 cup in total).
- After about 45 minutes, add garlic and cook for 1 to 2 minutes.
- Once you've reached your desired caramelization, deglaze onions with wine. Stir, scraping up any more brown bits on the bottom of the pot with a wooden spoon. Cook for 1 to 2 minutes. Stir in thyme, salt, and black pepper.
- Stir in flour and cook for 2 to 3 minutes.
- Pour in beef broth, Worcestershire sauce, and balsamic vinegar. Stir. Bring to a boil, then reduce the heat (to about medium-low heat) to a simmer. Cook for 15 to 20 minutes.
- Place oven-safe French onion soup bowls onto a sheet pan and portion soup into them.Note: Don't fill those bowls to the brim. Once you add the bread, it will displace some of the liquid.Note: With my bowls, I yielded 6 servings (or bowls). If your bowls are larger, the quantity you yield may vary.
- Brush each slice of bread with a little avocado oil (optional) and place on top of soup. Distribute the Gruyere cheese among the bread slices.
- Preheat the oven to 400 degrees Fahrenheit. Place the bowls of soup (that are on the sheet pan) into the oven and cook until the cheese is melted and a little golden brown (this should only take a few minutes). Carefully remove and garnish (if desired) with fresh thyme. Serve and enjoy!Note: If you don't have oven-safe bowls, omit putting the bowls into the oven. Rather portion out the soup and toast the bread with cheese separately, putting on top of the soup when serving.
A note on times provided: appliances vary, any prep and/or cook times provided are estimates only.
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