The Best French Onion Soup

This is the best French onion soup recipe, with rich caramelized onions, savory beef broth, and toasted French bread covered with gooey melted cheese. A professional chef’s recipe and tips for the richest, most flavorful French onion soup.

If you love a cup of French onion soup from your favorite restaurant, I can’t wait for you to try this version. It’s the best French onion soup I’ve ever made. Packed with flavorful, high-quality ingredients, it’s truly a spoonful of heaven.

Just dig through the melted cheese and the bread with your spoon and scoop up some of the warm broth and onions in one complete, mouthwatering bite. Marvel as your eyes close and you sigh in pleasure. It’s simple done right.

Professional Tips to Make French Onion Soup:

• Be patient. You will want to ensure your caramelized onions are perfectly  caramelized, almost more than you think is right. They will smell sweet with a note of caramel and should be a rich golden brown. Add a bit of water if they start to burn.
• Use the best ingredients. The secret to the best French food is high-quality ingredients. Be sure to use Cognac or brandy, quality cheese, fresh, in-season produce, and, of course, butter. 
• Make homemade broth. If you want to turn a good soup into a tantalizing culinary experience, you need to start with homemade beef broth. I’m talking about roasted veal and beef bones simmering for hours. Once you’ve tried it, you’ll never go back.

Ingredients

• Caramelized Onions: I recommend using sweet onions or yellow onions for this. You can find the directions for creating perfectly caramelized onions in this post.
• Flour: Regular, all-purpose flour will work best for this recipe. I don’t recommend using any specialized type of flour.
• Thyme: Fresh thyme is recommended for this recipe. You’ll want to pick and measure about a tablespoon of herbs without packing them down.
• Cognac: Cognac is brandy that has been made in Cognac. Just like in my best fruit cake recipe, the higher the quality, the better the taste of the dish. Since there is such a tiny amount in this recipe, you could buy those small airplane bottles or a pint. If Cognac is not an option, then opt for the best brandy you can afford. 
• Beef Broth: I recommend making your own homemade beef broth for the best flavor in this delicious soup. If you are unable to do so, an organic, low-sodium broth is the next best option. Use any leftover homemade stock to make some comforting butternut squash chili or this Tuscan Vegetable Sausage Soup!
• Kosher Salt: I like to use kosher salt in my cooking because it is less salty per teaspoon than other types of salt, like table salt and sea salt. This makes it easier to taste your food as you go and harder to oversalt.
• Black Pepper: A couple of grinds of fresh black pepper add a lovely bite to this soup. I like to use freshly ground black pepper rather than pre-ground pepper.
• French Baguette: Crusty French bread is best here. You can use a fresh baguette that you’ve just bought, or a leftover baguette from the day prior. The baguette will soften as it sits in the hot soup. If you’re looking for something softer and homemade, consider baking your own sourdough bread!
• Cheese: The best cheese for this recipe is actually three types of cheese. I primarily use the traditional Gruyère cheese, then mix in Swiss and fontina cheese. 

See the recipe card for full information on ingredients and quantities.

Variations

• All Gruyère Cheese: Gruyère cheese is traditional and you would not be remiss using all Gruyère, though the medley of Gruyère, Swiss, and fontina is delicious. If you wanted to get wild, because it’s definitely not traditional, you know from my white cheddar mac and cheese that I love gruyère with white cheddar as well!
• Bay Leaves: Some recipes recommend adding bay leaves to the beef broth while it simmers. You are welcome to try this variation and see if you like the results.
• Worcestershire Sauce: This is another common variation for French onion soup. If you find the soup to be too rich, you can try adding a dash of Worcestershire sauce to your next batch. If you’re not a fan of this addition, save your Worcestershire sauce for some Brown Sugar Glazed Meatloaf! 
• Chicken stock: Though it would have a different flavor profile, you could head in a chicken broth direction. In which case, follow my how to make chicken broth directions for the absolute best chicken broth!

How to Make the Best French Onion Soup

Use these instructions to make the best French onion soup every time! Further details can be found in the recipe card below!

Step 1: Caramelize your onions in a Dutch oven or thick-bottomed skillet.

Step 2: Once your onions are sufficiently caramelized (deep, rich caramel in color) sprinkle with the flour and stir to coat. Add the thyme, Cognac, two large pinches of kosher salt, and a few grinds of pepper. Stir to distribute the spices and allow to cook on low for a few minutes. 

Step 3: Add your beef broth and simmer over low heat for 30-40 minutes. This allows the flavors to develop. 

Step 4: While your soup is simmering, toast your bread on a baking sheet under the broiler. Watch it carefully! Toast until brown on each side. 

Step 5: Ladle an equal amount of soup into each broiler-safe, 13-ounce bowl.

Step 6: Top with several bread slices and then top with ¼ of the cheese mixture.

Step 7: Broil on a baking sheet until the cheese has melted and has started to bubble and brown. Serve immediately, but eat with care! It will be very hot.

Frequently Asked Questions

Before You Go

I hope you enjoyed this professional chef tested recipe. Check out our other delicious, chef-developed soup recipes!