This classic French onion soup recipe is easy to make and the perfect meal on a cold day. Make this soup from scratch in under an hour!
The key to making French onion soup as flavorful as possible is to caramelize the onions.
Because onions are naturally sweet, cooking them slowly over an extended period of time causes the sugars to caramelize. This creates an intense flavor that is both savory and sweet.
If you love rich onion flavor, make my recipe for Slow Roasted Onions. They’re marinated in red wine vinegar, brown sugar, and spices, then cooked until tender and caramelized.
Or, make a large batch for this soup recipe, then use the excess for French Onion Soup Baked Chicken and you’ll have complete meal.
INGREDIENT NOTES AND SUBSTITUTIONS
Note: This is just a partial list of ingredients. For the full ingredient list, see the recipe card at the bottom of this post.
- Onions – Because red onions are so sweet, it’s recommended to only use white or yellow onions to keep the balance of savory and sweet flavors.
- Beef stock – Replace with vegetable broth to make this recipe vegetarian.
- White wine – Choose a dry variety or substitute dry white vermouth or sherry instead.
- Cognac – While completely optional, using cognac adds another dimension of flavor and really brings out the richness of the beef stock.
- French baguette – This is a great opportunity to use up day-old bread since it will be toasted anyway. For extra flavor, rub the slices with oil and garlic cloves before toasting.
- Gruyere – If you can’t find this cheese, try Fontina, Swiss, and Provolone instead.
- Parmesan – Always buy fresh blocks of cheese and shred them yourself, as bagged shreds have a waxy texture and don’t melt properly. I highly recommend Parmigiano-Reggiano, but regular Parmesan is fine too.
Classic French onion soup recipe video
Watch this quick video to see us make this delicious soup, step by step!
HOW TO MAKE THE SOUP
Toast the bread
- Slice the baguette and toast the pieces in the oven.
- Once cooled, place them in the bottom of each ramekin. They can be left whole or broken into smaller pieces depending on their size.
Caramelize the onions
- Melt the butter in a large pot and stir in the onions.
- Cover and cook the onions until they’re soft, then uncover and continue cooking until fragrant and dark. Stir frequently to prevent any onions from sticking to the bottom of the pot.
Make the soup
- Once caramelized, stir in the flour and seasoning.
- Then, add the liquid and fresh thyme and simmer for a few minutes.
Bake and serve
- Divide the soup into the ramekins over the top of the bread, then sprinkle with cheese and bake.
- Once done, remove from the oven and discard the sprigs of thyme.
- Then, sprinkle chopped chives over each ramekin and serve with crusty French bread.
- Prevent oven burns – Set the ramekins on a baking sheet before placing them in the oven. This helps to catch any drippings from the soup and cheese bubbling over, which will smoke and burn if they land on the bottom of the oven.
- Storage – If you know you’ll have leftovers, only bake what you will be eating and refrigerate the rest straight from the pot. Let it cool, then transfer to an airtight container and store for 3 to 4 days.
- Freezing – You’ll also need to freeze the soup without the bread and cheese, so transfer to sturdy containers before baking. Leave room at the top for the liquid to expand and store for up to 3 months. Then, thaw in the refrigerator overnight before reheating.
- Reheating – Whether it was refrigerated or frozen, the reheating process is the same. Add the soup to ramekins with the bread and cheese and bake as directed. Or simmer the soup by itself on the stove for at least 15 minutes if you’d prefer.
Looking for something to serve along with the easy French onion soup? You can never go wrong with a small garden salad and a basket full of freshly baked soft breadsticks or cheese bread rolls!
Classic French Onion Soup
- 1/2 French bread baguette, toasted
- 4 tbsp butter
- 1 tbsp olive oil
- 3 lbs onions sliced (See Note 1)
- 1/2 tsp salt
- 1/4 tsp black pepper
- 2 tbsp all purpose flour
- 8 cups beef stock
- 1 cup white wine
- 3 sprigs of thyme
- 1/4 cup cognac optional
- 8 oz Gruyère cheese shredded
- 1/4 cup Parmesan cheese shredded
- 2 tbsp chives chopped
- Preheat oven to 400°F. Slice half of the baguette to have 2-3 slices per soup ramekin. Place bread slices on baking sheet and toast the bread slices until golden brown (See Note 2). Remove and allow to cool. Crumble into each soup ramekin on a baking sheet. Set aside.
- In a heavy bottom soup pot or Dutch oven over medium low heat add the butter and oil to melt.
- Add the sliced onions and stir. Cover with lid and cook for 15 minutes. Remove lid and turn heat to low. Cook, stirring often, another 15 minutes until onions are a dark golden brown.
- Add the salt, pepper and flour and cook another minute. Carefully pour in the beef stock and wine, stirring to combine. Add thyme, simmer 5 minutes.
- Ladle into prepared soup ramekins, top with the cheeses. Place in 400°F oven and bake for 15 minutes.
- Remove from oven and serve with chopped chives on top and crusty French bread.
- Use white or yellow onions, red are too sweet, but that is up to you.
- Rub with fresh garlic and oil prior to toasting, optional.
The information shown is an estimate provided by an online nutrition calculator. It should not be considered a substitute for a professional nutritionist's advice.