Name: Classic French Onion Soup Recipe
Prep time: 15 min
Cook time: 1 h
Total time: 1 h 15 min
Cuisine: French
Ingredients: 2 tablespoons olive oil; 6 medium yellow onions, sliced; 2 tablespoons butter; 1 tablespoon minced garlic; 8 cups beef broth; 1/4 cup dry sherry (optional); 1 teaspoon dried thyme; 1 teaspoon salt, or to taste; 1/2 teaspoon black pepper, or to taste; 8 slices French baguette; 2 tablespoons olive oil; 4 slices Gruyère cheese or provolone; 2 tablespoons grated Parmesan cheese

There’s just something so comforting about a warm bowl of rich, caramelized onions swimming in a savory broth, topped with melty cheese and crusty bread. This Classic French Onion Soup Recipe hits all those cozy notes perfectly—it's a timeless dish that feels like a warm hug from the inside out.

This image shows two white mugs with handles filled with French onion soup. Each mug has a dark brown onion broth as the bottom layer. On top of the broth are two toasted brown bread slices covered by melted golden cheese that is bubbly and slightly browned. A small green herb branch sits on top of the cheese in each mug, adding a fresh touch. The mugs are placed on a white marbled surface with some small scattered herb leaves around. The scene has a cozy and warm feeling. photo taken with an iphone --ar 2:3 --v 7

Jump to:

Why You'll Love This Recipe
Ingredients & Why They Work
Make It Your Way
Step-by-Step: How I Make Classic French Onion Soup Recipe
Top Tip
How to Serve Classic French Onion Soup Recipe
Make Ahead and Storage
Frequently Asked Questions:
Final Thoughts
Classic French Onion Soup Recipe

Why You'll Love This Recipe

Every time I make this Classic French Onion Soup Recipe, I’m reminded why it’s such a beloved dish across generations. It’s not just soup; it’s a labor of love that rewards you with deep, sweet onion flavor and gooey, golden cheese topping.

Caramelized onions: Slowly softening and browning the onions unlocks a natural sweetness that’s the heart and soul of the soup.
Simple ingredients: You probably have most of what you need in your pantry, making this recipe accessible yet impressive.
Melty, toasty topping: The combo of Gruyère and Parmesan browned on crispy baguette slices is pure magic.
Comfort food at its finest: This soup feels fancy but is perfect for cozy nights when you want to feel nourished and satisfied.

The image shows a white bowl filled with golden brown French onion soup topped with melted cheese that looks bubbly and slightly crispy. On top of the cheese, there is a layer of caramelized onions that are light golden and shiny. A spoon is lifting a portion of the cheese and onions from the bowl, showing the texture of the melted cheese stretching and the soft onions underneath. There is another white bowl with the same soup blurred in the background. The bowls sit on a white marbled surface, giving a clean and bright look. A small green herb garnish is placed on top of the soup, adding a touch of color photo taken with an iphone --ar 2:3 --v 7

Ingredients & Why They Work

Each ingredient in this Classic French Onion Soup Recipe plays a special role, coming together for a flavor that’s far greater than the sum of its parts. Here’s why these staples work so beautifully together, plus some tips for picking the best ones.

Flat lay of a medium pile of thinly sliced yellow onions, a small pool of golden olive oil in a shallow dish, a few pats of soft butter on a wooden board, a small bowl with minced garlic, a large bowl filled with rich dark beef broth, a small glass with amber dry sherry, a tiny heap of dried thyme, scattered coarse salt and black peppercorns, several slices of crusty French baguette brushed with olive oil, thin slices of Gruyère cheese, and a small mound of grated Parmesan cheese placed on a white marble surface, photo taken with an iphone --ar 2:3 --v 7

Yellow onions: Their natural sweetness ramps up beautifully with that long, slow caramelizing process.
Olive oil & butter: The combo adds depth—olive oil tempers the butter and helps the onions brown nicely.
Garlic: Just a touch to elevate the flavor without overpowering that onion focus.
Beef broth: Rich and hearty, it’s what gives the soup that classic umami punch.
Dry sherry (optional): Adds a subtle boozy note that brightens the soup and deepens the complexity.
Dried thyme: This herb gives a subtle earthiness that complements the sweet and savory balance.
French baguette: Toasted until golden, it creates the perfect vehicle for the ooey-gooey cheese topping.
Gruyère cheese: Melts beautifully with a slightly nutty flavor that’s classic in French onion soup.
Parmesan cheese: Sprinkled on top for a sharp, salty finish that contrasts nicely with the creamy Gruyère.

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Note: You'll find the complete list of ingredients, along with their exact measurements, in the printable recipe card at the bottom of this post.

Make It Your Way

I love that you can easily personalize this Classic French Onion Soup Recipe to suit your tastes or what you have in the kitchen. Whether it’s extra cheese or a splash of a different wine instead of sherry, this soup is forgiving and flexible.

Variation: I sometimes swap the dry sherry with a dry white wine like Sauvignon Blanc for a brighter flavor that still complements the savory broth perfectly.
Dietary tweak: For a vegetarian take, use mushroom broth instead of beef—it’s an easy swap that still delivers great umami depth.
Spice it up: Try adding a pinch of smoked paprika or a dash of cayenne for some subtle heat that warms things up.
Cheese choice: If you can't find Gruyère, provolone or Emmental cheese work wonderfully and melt just as well.

Step-by-Step: How I Make Classic French Onion Soup Recipe

Step 1: Slowly Caramelize the Onions

Start by heating olive oil in a large pot over medium-high heat and adding your sliced onions. Stir them every few minutes so they soften evenly without burning. After about 5-7 minutes, reduce the heat to medium-low and be patient—this part takes 15 to 25 minutes until those onions turn a deep golden brown. This slow caramelization is key; it brings out the sweetness you'll love in every spoonful.

Step 2: Build Flavor with Butter and Garlic

Once the onions are beautifully caramelized, stir in butter and minced garlic. Let the butter melt and garlic get fragrant—this simply takes about 2 minutes but deepens the taste wonderfully without overpowering the onions.

Step 3: Simmer the Soup

Pour in beef broth and your optional dry sherry, then season with thyme, salt, and pepper. Bring everything to a simmer before lowering the heat to keep a gentle bubble going for 20 to 30 minutes. This allows those flavors to blend into a warm, savory hug in a bowl.

Step 4: Prepare the Crunchy Croutons

While the soup simmers, brush baguette slices with olive oil on both sides. Broil them for 2-3 minutes on each side until golden brown and crisp. Keep an eye on them here—they can go from perfect to burned in seconds!

Step 5: Assemble and Broil the Soup

Ladle the hot soup into oven-safe bowls placed on a baking sheet. Top each bowl with two toasted baguette slices, then pile on the Gruyère slices and sprinkle with Parmesan. Slide the tray under the broiler until the cheese bubbles and turns golden—usually about 2-3 minutes. Watch closely so it doesn’t burn.

Step 6: Serve Immediately

Serve your Classic French Onion Soup Recipe right away, while that melty cheese is warm and gooey. I promise it’s worth savoring right out of the oven.

Top Tip

From my experience, the secret to mastering this Classic French Onion Soup Recipe is patience and careful attention during the caramelization and broiling steps. Those moments truly make or break the soup.

Low and Slow Caramelization: Resist the urge to turn up the heat to speed things up. High heat burns the onions before they soften properly. Stick to medium-low and stir regularly for that perfect caramel color and flavor.
Watch the Broiler: Broilers vary wildly. Keep the oven door slightly open and watch the cheese carefully to avoid turning it bitter and burnt.
Bread Tips: Choose a sturdy baguette — one that holds up under the soup without getting soggy too fast.
Season Gradually: Taste as you go, especially with salt. The broth and cheese add saltiness, so you might need less than you expect.

How to Serve Classic French Onion Soup Recipe

Garnishes

I like to keep it simple here—just the toasted baguette topped with Gruyère and Parmesan. But sometimes, a sprinkle of fresh thyme leaves on top before serving adds a lovely aroma and freshness.

Side Dishes

This soup is so rich I usually pair it with a crisp green salad to balance the flavors. A light vinaigrette and some crunchy nuts on the salad complement the soup’s deep, savory notes nicely.

Creative Ways to Present

For special occasions, I sometimes serve the soup in mini oven-safe crocks topped with little rounds of baguette and cheese. It looks elegant and portion-controlled, perfect for dinner parties or cozy date nights.

Make Ahead and Storage

Storing Leftovers

I usually keep leftover soup (without the bread and cheese) in an airtight container in the fridge for up to 3 days. This way, it stays fresh and the flavors even deepen as it rests.

Freezing

This Classic French Onion Soup Recipe freezes very well if you leave out the bread and cheese. Freeze in portions for up to 3 months, then thaw in the fridge before reheating gently on the stove.

Reheating

When reheating leftovers, do it slowly over low heat to prevent the onions from tasting bitter. Add fresh toasted bread and cheese right before serving for the best experience.

Frequently Asked Questions:

Can I make Classic French Onion Soup Recipe vegetarian?

Absolutely! Swap the beef broth for a rich vegetable or mushroom broth and skip the meat-based additions. It still turns out flavorful and comforting.

What’s the best cheese for French onion soup?

Gruyère is the traditional choice thanks to its superb melting quality and nutty flavor, but Emmental, provolone, or mozzarella can work if you can’t find it. Parmesan adds a sharp finish on top.

How long does it take to caramelize onions properly?

Caramelizing onions for this soup usually takes between 20 to 30 minutes over low to medium-low heat. Patience during this step is essential to get that deep sweet flavor.

Can I prepare this soup ahead of time?

Yes! The soup base can be made a day in advance. Just hold off on adding the toasted bread and cheese until you're ready to serve to keep them crisp and melty.

Final Thoughts

I always find that this Classic French Onion Soup Recipe offers more than just a meal—it’s a simple ritual that fills the kitchen with incredible aromas and the heart with warmth. Once you get that caramelized onion flavor just right, everything else falls into place. Trust me, when you share this bowl of cozy goodness with friends or family, it’s guaranteed to become one of your favorite comfort foods too.