French Onion Soup
French Onion Soup, or Soupe à l’Oignon Gratinée, is a French classic that is guaranteed to impress! A rich and hearty soup, made with onions that are caramelized to perfection, topped with crusty bread and two types of cheese and then gratinéed until ooey-gooey, browned and completely decadent. Perfect for a romantic dinner for two or for an elegant dinner party!
Looking to add more classic French recipes to your repertoire? I recommend you also check out my Sausage and Chicken Cassoulet, French Leek Tart, Boeuf Bourguignon and Gougères.
Welcome to what I am calling a series of “sexy recipes” leading up to Valentine’s Day!
To start, one of the sexiest recipes of all times: French Onion Soup. Because who can resist a bowl of this decadent soup, especially when topped with garlic bread and bubbly cheese?
“Did you say garlic bread? For Valentine’s Day dinner?”
Yes, I did! But don’t worry. It is only slightly garlicky, enough to give the bread an interesting flavor but not garlicky enough to send your V-Day date running for the hills because of your vampire-repelling breath!
And as for the onion breath… Well, I can’t help you with that. There are 3 pounds of onions in this recipe. But I’ll be damned if you care after tasting this insanely delicious soup! 😋
What is French Onion Soup?
French Onion Soup is a classic French soup made of onions and beef stock, which is often served gratinéed with bread covered with cheese.
Onion soups date as far back as Ancient Rome, prepared for the first time over 8,000 years ago. However, the version that became popular in Parisian restaurants (and eventually the world) originated in Paris in the 18th century.
There are two interesting theories regarding the creation of this soup, both involving King Louis XV and his family.
The first says that he returned to his lodge from a hunt to find that his cupboards were bare except for onions, butter and champagne. So he and his great-aunt, who was staying with him, threw everything in the pot and created the first classic French onion soup recipe. In another variation of this version, King Louis was actually hosting a party in his hunting lodge when he became ravenous, which led him to raid the lodge’s pantry trying to find food.
The second legend claims that the Duke of Lorraine (Stanislas Leszczynski), who was Queen Marie’s father and, therefore, Louis XV’s father-in-law, was the one who discovered this onion soup. While he was on his way to the Palace of Versailles, he stopped at an inn called La Pomme d’Or in Châlons-en-Champagne, where he was served the soup. He found it so delicious that he went to the kitchen to ask to see how it was made. And even though “the smell of the onion […] brought great tears to his eyes”, he watched Nicolas Appert (the chef) dice lots of onions and copied down the whole recipe. Those who believe this version use as proof the fact that Nicolas Appert dedicates his recipe to the duke in his cookbook (published in 1831) by naming it onion soup à la Stanislas.
That being said, it was in restaurants surrounding les Halles – the Poule au Pot, Chez Baratte, the Pied de Cochon – that this soup gained its popularity, due to the addition of one key element: the gratinée.
The French Onion Soup is considered the ultimate hangover cure. When it was introduced to the Parisian court, it gained the nickname “the soup of the drunkards” because people realized it was very effective at covering the smell of alcohol after a night of drinking. To this day, it is tradition in France to serve this soup at weddings – long after the cake has been served – to prevent a hangover the next day.
To make this French Onion Soup recipe, you will need:
- Onions – I use yellow onions in this recipe, as they are inexpensive, slightly sweet and not overly bitter. You can use sweet onions if you prefer, but the soup will be a bit sweeter. You can also add a combination of several onion types, for a more complex flavor.
- Beef Stock – I prefer using beef stock than broth. Beef stock is thicker and more flavorful, making the soup richer and… well, sexier! 😉 Homemade is preferred, but if you don’t have any on hand, store-bought works too. Just splurge on the good stuff! Sometimes you can buy beef stock straight from your butcher.
- White Wine – We’ll use the white wine to deglaze the pot. It also adds acidity, which helps balance the sweetness and savoriness of the other components of this French onion soup. Use something that you would drink and, please, stay away from your grocery store’s “cooking wines”.
- Sherry – Sherry is an aged, fortified (with brandy) wine. We are using dry sherry (Fino), which brightens the soup and adds a touch of nuttiness due to its sharp, delicate bouquet slightly reminiscent of almonds. I like adding both white wine and sherry for depth of flavor, but if you don’t have any on hand – by all means – just omit it!
- Herbs – A few sprigs of fresh thyme and a couple of bay leaves (fresh or dried).
- Oil and Butter – Yes, you’ll need both. Butter adds flavor, but it has a very low smoke point and it can burn over heat. Adding a little bit of oil will keep that from happening.
- Flour – To thicken the soup.
- Worcestershire Sauce – This is not a traditional ingredient in French onion soup. However, I personally think it adds a much welcomed umami, depth and savoriness. Without it, this soup is borderline bland to my taste.
- Salt and Pepper
- Cheese – Gruyère and Parmesan are the classic choices for this soup. The Gruyère melts beautifully and adds a delicious nutty flavor while the parmesan adds yet another layer of umami-ness. If you must substitute, other cheeses you can use are: Jarlsberg, Raclette, Beaufort, Comté, Gouda, Mozzarella or even Provolone.
- Bread – Any kind of crusty bread will do. I like a rustic sourdough loaf (or even a loaf of Italian bread), but a nice French baguette will also work. If using the baguette, you might need two slices per bowl, depending on how wide your ovenproof bowls are.
- Garlic – Another not traditional ingredient. But rubbing a clove on garlic on the bread slices really bring this French onion soup to a whole new level!
No sugar, Olivia?
No, there is no need to add sugar to caramelize onions. Onions already have natural sugars that are intensified when they are slow cooked.
The sherry, albeit dry, also brings a slight sweetness that helps balance the bitterness from the onions.
If, at the end, you taste the soup and think it is bitter and could benefit from a pinch of sugar, by all means, go for it! I prefer you use the sugar to correct the seasoning at the end than add it in the beginning and end up with a too sweet soup that you won’t be able to fix.
How to Make French Onion Soup
French onion soup, like several other French recipes, can seem intimidating. But it doesn’t have to be!
This is an easy recipe and pretty much foolproof, if you don’t cut corners. If you caramelize the onions properly and use good wine and good beef stock, you will have an onion soup that is so delicious that it doesn’t even need the bread and cheese.
Ha! Just kidding. The bread and cheese definitely make it extra special!
Recommended tools and equipment: Chef’s knife (for slicing the onions), Dutch oven, baking sheet, parchment paper, kitchen brush, oven-proof soup bowls.
Here’s how I make this French Onion Soup recipe. As always, you will find the printable (and more complete) version of the recipe at the end of this post!
Step 1: Make the onion soup.
- Start by slicing your onions uniformly, so they cook evenly. You should slice them thin but not too thin, about 1/8-inch thick. Paper thin onions will break down fast and can almost disintegrate in the soup.
- Heat the oil and butter, then add the onions and a pinch of salt. Cover and cook for 15 minutes. Don’t disturb it! The onions will soften and you might begin to see some browned bits on the bottom of the pot.
- Uncover and cook, stirring occasionally (and more often at the end), until they are caramelized, meaning they are a dark golden-brown color. That usually takes anywhere from 35 to 45 minutes, but it can take longer depending on your onions, cookware, stove, etc. If you notice that the onions are browning too quick, lower the heat. You don’t want to risk burning them!
- Add the white wine and sherry and scrape the browned bits from the bottom of the pan (the “fond”). Once the wine begins to boil, add the flour and a pinch of salt and pepper. Cook just for a minute, to get rid of the raw flour taste.
- Pour in the stock, Worcestershire sauce, bay leaves and thyme. I like to tie the thyme sprigs together with kitchen twine to make it easier to dispose of them later.
- Simmer the soup, covered, for 20 minutes. Discard thyme sprigs and bay leaves. Then taste and adjust seasoning.
Step 2: Make the garlic bread.
- Arrange the slices of bread on a baking sheet. I like to cover it with parchment paper for easier cleaning later.
- Brush with olive oil and bake until golden.
- As soon as the bread is out of the oven, rub a garlic clove on the top side of each slice. Trust me, this simple step really makes a whole lot of difference in this recipe! The garlic taste is not too pronounced, but makes everything better.
Step 3: Assemble the soup bowls.
- Place ovenproof bowls or ramekins on the baking sheet and fill them with the onion soup.
- Place the bread slices over the soup, then top with the Gruyère and the parmesan cheeses.
- Broil until the cheese is melted.
- Garnish with thyme and serve!
- Take your time caramelizing the onions. The deep dark, beautifully caramelized onions are the star of the show here, so don’t rush as this process can take up to one hour.
- The caramelized onions should be a rich golden brown. Some recipes will call for them to be almost black, but I find that the soup is then too bitter.
- I recommend a Dutch Oven to make this French onion soup recipe. If you don’t have one, choose a pot that is wider than it is deep, as you want the onions to have enough space to caramelize.
- If you find that the browned bits from the bottom of the pot are getting burned while the onions are caramelizing, and not lifting off by scrapping them, it is okay to use water to deglaze the pot, as many times as needed during the caramelization process.
- If you don’t have oven safe bowls, don’t worry! You can melt the cheese over the bread on a baking sheet and then top the soup with the cheesy breads.
In my humble opinion, when served as an entrée, this soup is already filling on its own. But if you wish to complement it, a simple green salad – or even a more extravagant French salad – is a good option.
This soup can also be served as an appetizer. Perhaps as the beginning of a wonderful French feast, featuring French Mustard Chicken or Roasted Chicken with 40 Cloves of Garlic, green beans and a side of Potato Gratin Dauphinois.
French Onion Soup Wine Pairing
This French onion soup recipe can be paired with either white or red wine.
According to Wine Folly, a classic pairing of French onion soup and Beaujolais, preferably a Cru, is the way to go. They suggest Fleurie, Saint-Amour or Chiroubles AOCs as their plum, cherry and peach flavors complement the distinct sweet flavor from the caramelized onions.
If you choose to go with a red, a Sangiovese, like Rosso di Montalcino, has the right acidity to cut through the richness of the soup, pairing beautifully with the intense beefiness and softening the fat from the cheese with its tannins.
Frequently Asked Questions
Yes, you can make the onion soup part of this recipe up to 2 days ahead. Refrigerate in an airtight container until ready to use, then reheat before assembling the bowls. You can also make the garlic bread a day ahead and store it at room temperature.
Yes, the soup (without bread and cheese) can be frozen for up to 3 months.
Yes, just omit the white wine and sherry and use the stock to deglaze the pot.
More Soup Recipes
French Onion Soup Recipe
- 3 tablespoons olive oil, divided
- 4 tablespoons unsalted butter
- 3 pounds yellow (or sweet) onions, peeled and sliced about 1/8-inch thick
- Kosher salt and freshly ground pepper, to taste
- ½ cup dry white wine
- 1 tablespoon dry sherry
- 2 tablespoons all-purpose flour
- 2 quarts beef stock, homemade or store-bought
- 2 bay leaves
- 4 sprigs fresh thyme
- 3 tablespoons Worcestershire sauce
- 4 slices rustic crusty bread, sliced 1-inch thick
- 1 clove garlic, peeled and slightly smashed to release oils
- 6 ounces Gruyère cheese, shredded
- ¼ cup grated parmesan cheese
- Garnish: fresh thyme
Make the Onion Soup
- In a large Dutch Oven, over medium heat, heat 2 tablespoons olive oil and the butter. Once the butter has melted and begins to foam, add the sliced onions and 1 teaspoon of kosher salt. Stir to combine, then cover and cook for 15 minutes, undisturbed.
- Uncover and continue cooking, stirring occasionally, until the onions are caramelized, about 35 – 45 minutes. Lower the heat if you find that the onions are browning too quickly. Season with salt and pepper.
- Pour in the white wine and dry sherry, scraping all the browned bits from the bottom of the pot. Once boiling, stir in the flour and a pinch of salt and pepper. Cook for about 1 minute or until the mixture thickens.
- Add the beef stock, Worcestershire sauce, thyme and bay leaves. Bring to a boil, then lower to a simmer, cover and cook for 20 minutes. Discard thyme sprigs and bay leaves.
- Taste and adjust seasoning as needed.
Toast the bread
- While the soup is simmering, preheat oven to 450ºF.
- Arrange the bread slices on a baking sheet, covered with parchment paper.
- Brush the bread on both sides with the remaining olive oil.
- Toast the bread in the oven for 10 – 15 minutes, flipping halfway through, until golden brown.
- As soon as the bread is out of the oven, rub the garlic on the top side. Reserve.
Assemble the French Onion Soup Bowls
- Preheat broiler and adjust oven rack to top position.
- Place 4 (or 8 if making appetizer sized soups) ovenproof bowls or ramekins on the baking sheet. Ladle the soup into the bowls, dividing equally, then top with the bread slices, garlic rubbed size up. Top with the Gruyere and parmesan cheese.
- Place bowls under the broiler and broil until the cheese is melted and is browned in spots.
- Garnish with thyme and serve!