This traditional French Onion Soup recipe has warm baguettes topped with hot, melted Gruyere cheese. High quality beef broth, a splash of wine, and perfectly caramelized onions are the secrets to this classic recipe. PLUS, check out how you can prepare this recipe in the Crock Pot.
French Onion Soup
In case you didn’t know, I am a soup fanatic. And there are so many different ways there are to make a traditional, homemade french onion soup recipe. I have tried them all, I’ve researched a lot, and I’ve finally got this recipe totally nailed down.
The secret to making the best French Onion Soup is to properly caramelize the onions and to use high-quality ingredients. That means using good butter, wine, broth, fresh baguettes, and cheese.
But don’t worry- I’ve offered great substitution options if you prefer not to use alcohol or would like more budget-friendly cheese options. I’ll even show you how the Slow Cooker can help you caramelize those onions!
Here are all of my KEY tips on making this recipe:
Use a Combination of Yellow and Sweet Onions
- Each type of onion adds a different element of flavor. Combining the two allows you to enjoy the best of what each has to offer.
- I like to use 2 sweet (vidalia) onions and 4 yellow onions, they weigh a solid 5 pounds total.
- Use a madoline slicer to cut the onions quickly and evenly.
Use Dry White Wine
- I have tried several different wines for this recipe and I find dry white wine to be the best.
Best Dry White Wines for Cooking:
- Sauvignon Blanc
- Pinot Grigio
- Unoaked Chardonnay
If you prefer to make this without wine:
- You can substitute 3 Tablespoons white wine vinegar + chicken or beef broth to make 3/4 cup.
Best Cheese For French Onion Soup
- Gruyere cheese is best.
- Other cheese options include Comte, Emmental (Swiss), Provolone, or Mozzarella.
Use High Quality Beef and Chicken Broth
- Some recipes call for using only beef broth, but adding chicken broth creates a greater depth of flavor.
- Homemade or High-quality commercial beef broth is a must. You can also try to purchase a private label from a local butcher.
- Homemade chicken broth is also ideal for this soup.
How to Caramelize Onions
Caramelizing onions is very easy, it takes patience more than skill. Follow the simple steps below and the rest will take care of itself.
Don’t cut the onions too thin
- You want 1/4 inch slices, as they will shrink down and you don’t want them to be too thin or stringy.
Coat the onions generously in butter.
- Use a set of tongs makes them easy to toss around in the pot.
Cook them low and slow
- Cook the onions over medium-low heat. This process takes some time but the end result is well worth it.
Use more onions than you think
- Onions made up of over 80% water. They shrink down considerably as they cook, as you will see below.
- I use 5 pounds in this recipe.
Watch These Onions Caramelize. Each photo was taken 20 minutes apart.
Caramelizing Onions in the Crock Pot
The benefit of caramelizing the onions in the Crock Pot is that you don’t have to stir them while they reduce and you can get most of the work done overnight. They’ll need to cook on low for 10 hours.
Note: To fully caramelize them, you will need to transfer them to a pot on the stove at the end with some additional butter and some of the juices from the Crock Pot over medium-high heat for 10-15 minutes. You will then finish the soup on the stove top as well.
- Melt 4 Tablespoons of butter in the Crock Pot. Add the onions and toss to coat. Cook on low for 10 hours.
- Melt 2 Tablespoons of butter in a large pot on the stove over medium-high heat. Wait until it begins to foam. Add the onions and cook for 10-15 minutes.
- Decrease heat to medium. Add the white wine and cook for an additional 2-3 minutes. Pour in the beef broth, chicken broth, Worcestershire sauce, and add the bay leaves and thyme.
- Simmer for another 45 minutes on the stove with the lid cracked. OR, transfer back to the Slow Cooker and cook for 2-3 hours on high or 4-6 hours on low.
Instant Pot Method
Yes, it’s true! You can make this in the Instant Pot! (As featured on MSN.)
Make-Ahead Method
- There is probably no better soup to make ahead of time than this. This soup can be stored in an airtight container for up to three days prior to serving.
- The soup can be reheated on the microwave, Slow Cooker, or stove top, and the baguettes and cheese can be toasted/melted separately and added to the soup once ready to serve!
Freezing
This is a great freezer meal.
- Let it cool prior to freezing and store it in an airtight container.
- It’s best if used within 3 months of freezing.
- Freeze only the soup, don’t include bread/cheese with it.
Try These Next!
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French Onion Soup
Ingredients
- 4 large yellow onions,, see notes for pound conversion
- 2 large sweet onions, Vidalia
- 6 Tablespoons butter
- 2 sprigs fresh thyme
- 2 Bay leaves
- ¾ cup dry white wine, Chardonnay or Pinot Grigio
- 3 tablespoons flour, optional
- 4 cups beef broth, high quality is key
- 1 beef bouillon cube, or 1 tsp Better Than Bouillon
- 1.5 cups chicken broth
- 1 teaspoon Worcestershire sauce
- Salt/Pepper, to taste
- 1 baguette
- 3 Tablespoons olive oil, optional
- 6 slices Gruyere cheese
Instructions
- Slice the onions into ¼-inch slices, (no thinner). They'll reduce in size quite a bit and you don’t want them to be too stringy. (Using a mandoline slicer makes this much easier).
- Melt the butter in a large soup pot or dutch oven over medium-low heat. Wait until it begins to foam, this allows water to evaporate out, leaving the butter more clarified and smooth.
- The onions will caramelize slowly, up to 2 hours or longer. Stir them every 10-15 minutes. As the onions caramelize, they may leave some brown residue at the bottom of the pot. Add a splash of wine and use a silicone spatula to 'clean' the bottom of the pot. Repeat as needed throughout the cooking process
- When the onions are nearly done, sprinkle flour over them and cook for 2 minutes. Add any remaining wine and increase the heat to medium-high. Toss the onions more frequently. They are done when they are richly brown and sweet.
- Add the beef broth, beef bouillon, chicken broth, Worcestershire sauce, bay leaves and thyme. Simmer over medium heat for 45 minutes with the lid cracked.
- While the soup simmers, preheat the oven to 350° F.
- Slice the baguette into ½ inch thick slices. Brush the tops with olive oil and bake for about 5 minutes.
- Increase the oven temperature to 450° F. Top each baguette with cheese and bake in the oven until the cheese melts and begins to bubble and brown.
- Remove the bay leaves and thyme stems. Season to taste with salt and pepper.
- Ladle the warm soup into each bowl and top each of them with the warm baguettes. Serve!
Notes
- You should use about 5 pounds of onions (total) for this recipe.
- If you prefer not to use Wine, you can substitute 3 Tablespoons white wine vinegar + chicken or beef broth to make 3/4 cup.
- Other cheese options include Comte, Emmental (Swiss), and/or Provolone.
Crock Pot Method:
Note: The stove top does come into play with this method as the heat is needed to fully caramelize the onions at the end. However this method allows you to almost fully caramelize the onions overnight without stirring.- Melt 4 Tablespoons of butter in the Crock Pot. Add the onions and toss to coat. Cook on low for 10 hours.
- Melt 2 Tablespoons of butter in a large pot on the stove over medium-high heat. Wait until it begins to foam. Add the onions and cook for 10-15 minutes.
- Decrease heat to medium. Add the flour and cook for 2 minutes. Add the white wine and cook for an additional 2-3 minutes. Pour in the beef broth, chicken broth, Worcestershire sauce, and add the bay leaves and thyme.
- Simmer for another 45 minutes on the stove with the lid cracked. OR, transfer back to the Slow Cooker and cook for 2-3 hours on high or 4-6 hours on low.
Seriously one of the best onion soups we’ve ever had. Prepared just as written with Provolone cheese because it’s what I had. Used the white wine and added the splash of Worcester sauce.
Hi Diane! I am SO happy that you enjoyed this soup, it is always such a treat in our house. Thank you SO SO much for taking the time to leave a comment and a rating, you are the best. Much appreciated. Take care!! -Stephanie
Can I freeze the leftovers? Even though there are five people in my family, my son and husband aren’t big onion people, I don’t want to waste any leftovers!
You sure can! Here are the instructions:
-Let it cool prior to freezing and store it in an airtight container.
-It’s best if used within 3 months of freezing.
-Freeze only the soup, don’t include bread/cheese with it.
Thank you!
Love this recipe I’ve made it twice
Awesome! So happy to hear that George! Thank you for taking the time to leave a review! -Stephanie
This is really outstanding!
Hey Patricia! I’m so happy that you liked it and REALLY appreciate you taking the time to leave a review, thank you! Stay safe and take care! -Stephanie
This was so delicious!
Hey Amanda! AWESOME! I’m so happy that you enjoyed it!! Thank you for taking the time to leave a rating!! 🙂 -Stephanie
I watched the video on the side and I’m wondering if you’ve missed a step in the instructions. Are we supposed to cooke the baguette once before putting the cheese on top? For how long?
Hey Michaela, I don’t usually bake them before placing the cheese on top, if you’d like to firm them up a little bit first you can pop them in for a minute or so first!
So why does the recipe say to heat the oven to 350 and then put it on broil? Either way, I made this yesterday and it is awesome! It exceeded my expectations. I’m generally not a good cook and nothing I make ever tastes as good as I’ve had elsewhere, but this was the major exception
You are SO right! I updated the instructions to indicate to bake them at 350 for 5 minutes to firm them up a bit before adding the cheese, at least one of us is paying attention! I don’t know where that part of the instructions went! Thank you Michaela and I’m so happy that the soup came out well for you, you made my day! -Stephanie
Absolutely delicious! The time it takes to caramelize the onions “low and slow” is well worth the wait. I didn’t have thyme on hand so I added a pinch of rosemary. I added a splash of Worcestershire Sauce when adding the broth. I will absolutely be making again and recommending this recipe to family/friends. Thank you for the detailed directions!
Hey Lauren!! I’m so so happy you enjoyed this recipe! And I really appreciate the review as well, it means a lot! Thank you!! ❤️-Stephanie
Just made this recipe and I have to say, it’s the best I’ve ever had!
Hi Martha! I am Sooo happy that you enjoyed this soup! You made my day! Thank you so much for taking the time to leave a comment here! -Stephanie
I am in the process of making the French onion soup it smells so wonderful. Broth is made, onions are almost ready Rest of ingredients are ready to be added . Carl and I can’t wait for dinner just waiting for our daughter to show up to help have dinner with us.
That sounds wonderful Susan! I’m a bit jealous!!! I hope you LOVE it! Enjoy your dinner!! ❤️
Can you give a more specific measurement on the onions, such as in pounds? The size of onions can vary greatly. You mentioned somewhere about 10 cups, but a total of 6 onions for me would be about 2 cups!
Thank you.
Hey Stephanie, I would use 5 pounds, I’ll make that clearer in the recipe!
Delicious and easy soup recipe, adding it to my arsenal of favorites. Sharing on my FB page and IG, thanks for sharing!
Hi Katie! I’m sooo happy to hear that!! Thank you so much for taking the time to let me knew what you thought of it! 🙌🏻 -Stephanie