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; 2 tablespoons grated Parmesan cheese

If you’ve ever craved that warm, cozy bowl of rich, caramelized onion goodness, you’re in the right place. This Classic French Onion Soup Recipe brings the comforting flavors of a Parisian bistro right into your kitchen — perfect for chilly nights or whenever you need a little delicious comfort.

French onion soup - Two white bowls filled with rich brown soup form the base layer, topped with two slices of toasted bread soaked in the soup, golden to light brown and bubbly from melted, browned cheese. The cheese layer has a creamy yellow color mixed with some crisp, darker golden spots. A small sprig of fresh green thyme is placed on top of the cheese for garnish. The bowls sit on a white marbled surface with a few scattered thyme leaves nearby. 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

French onion soup is one of those classic dishes that seems fancy but is surprisingly simple to make at home. I adore this version because the onions caramelize to golden perfection, giving the soup a deep, rich flavor, and the cheesy bread topping? Pure magic.

Perfect Caramelization: The slow-cooked onions develop a sweet, complex flavor that's key to authentic soup.
Simple Ingredients: You only need a handful of pantry staples, making it easy to whip up anytime.
Cheesy, Crunchy Topping: Toasted baguette slices with melted Gruyère and parmesan create an irresistible finish.
Comfort Food Classic: This soup warms you inside out and invites lingering conversations around the table.

French onion soup - The image shows a white ceramic bowl filled with dark brown onion soup, topped with a golden-brown melted cheese layer that covers toasted bread slices. A spoon lifts a portion from the bowl, revealing soft cooked caramelized onions with stringy, melted cheese stretching from the soup. There is a green herb sprig on the surface of the soup as garnish. The bowl is placed on a white marbled surface, and there is another similar bowl blurred in the background. 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, from the sweet onions to the savory broth and melty cheese. Here's why these choices matter and some tips to make sure you get the best results.

French onion soup - Flat lay of golden sliced yellow onions with their translucent layers shining softly, whole garlic cloves with papery white skins and some minced garlic scattered delicately, glossy sticks of pale butter, fresh sprigs of dried thyme with tiny green leaves, rich dark beef broth in a small glass container catching the light, crusty French baguette slices with a warm golden crust and a textured crumb, smooth pale yellow slices of Gruyère cheese slightly curled at the edges, and fine shreds of snowy white Parmesan cheese sprinkled artistically, all arranged naturally with a balance of colors and textures, placed on white marbled surface, photo taken with an iphone --ar 2:3 --v 7

Yellow onions: These have just the right balance of sweetness and sharpness and caramelize beautifully.
Olive oil & Butter: The combo helps the onions brown evenly and adds richness to the soup.
Garlic: Adds a gentle aromatic flavor without overpowering the onions.
Beef broth: Gives the soup a deep, hearty base. I like to use a good quality or homemade broth for best flavor.
Dry sherry (optional): Adds a subtle depth and slight sweetness that lifts the broth.
Dried thyme: Classic herb pairing that complements the savory elements.
Salt & Black pepper: Essential for balancing all the flavors perfectly.
Baguette: Sturdy enough to hold up under the soup, and toasts crispy for that perfect bite.
Gruyère cheese: Melts wonderfully, offering a nutty, rich topping that’s authentic and delicious. You can swap with provolone if preferred.
Parmesan cheese: Adds a sharp, tangy note that complements the Gruyère beautifully.

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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

While I love the classic version, I often play around with little tweaks depending on the season or what’s in my pantry. Don’t be afraid to make this soup your own; cooking is all about making flavors that sing to your taste buds.

Variation: Sometimes I swap the beef broth for mushroom broth to make it vegetarian-friendly, and honestly, it’s just as good! The key is in the caramelized onions.
Spice it Up: A pinch of smoked paprika or cayenne pepper can add a subtle kick if you like a little heat.
Cheese Options: If Gruyère isn’t around, I’ve also had great success using Emmental or even a sharp cheddar for a different twist.
Alcohol-Free: If you prefer, just skip the sherry and add a splash of apple cider vinegar at the end to brighten the flavor.

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, then add your sliced yellow onions. Cook them until they start to soften—about 5 to 7 minutes. Then lower the heat to medium-low and let them cook slowly, stirring every few minutes. This slow caramelization, lasting about 15 to 25 minutes, is what transforms sharp onions into sweet, deeply flavored gold. Patience here is your best friend; don’t rush or turn up the heat or you risk burning them.

Step 2: Add Butter and Garlic

Once your onions are beautifully golden and tender, stir in the butter and minced garlic. The butter adds a luxurious richness and the garlic a gentle aroma. Cook this mixture for around 2 minutes until the butter melts and the garlic becomes fragrant, but be careful not to let the garlic burn—it can turn bitter fast!

Step 3: Build the Broth

Pour in the beef broth and the optional dry sherry, then add thyme, salt, and black pepper. Bring it all to a gentle simmer, then lower the heat and let it bubble softly for 20 to 30 minutes. This is where the flavors meld together — the sweet onions infuse the broth, creating that signature depth you want in a French onion soup.

Step 4: Toast the Baguette

While the soup simmers, preheat your broiler and line up your baguette slices on a baking sheet. Brush them with olive oil on both sides — this makes them crispier and golden when toasted. Broil for 2 to 3 minutes per side, but watch closely! Bread can go from toasted to burned in a flash. These toasty slices will soak up the soup and hold the cheese perfectly.

Step 5: Assemble and Broil

Spoon the hot soup into oven-safe bowls placed on a baking sheet. Top each bowl with two slices of toasted baguette, then add a slice of Gruyère and a sprinkle of parmesan cheese. Pop the whole tray under the broiler for 2 to 3 minutes until the cheese is bubbling and beautifully browned. Keep a close eye so it doesn’t burn—you want just those golden brown spots!

Step 6: Serve Immediately

This soup is best enjoyed right away while that cheesy topping is still melty and warm. Grab a spoon, dig in, and savor the layers of flavor and texture in every bite.

Top Tip

From my experience making this Classic French Onion Soup Recipe multiple times, mastering the caramelization step is the real game-changer. Here are a few tips to help you nail it every time.

Low and Slow is Key: Don’t rush the onions—cook them on low heat, stirring frequently to develop that perfect golden color and sweetness.
Use a Wide Pan: A wide-bottomed pot spreads the onions out, giving them more surface area to brown evenly.
Watch Your Heat: If the onions begin to burn, lower the heat immediately and add a splash of water or broth to deglaze the pan.
Don’t Skip the Broth Quality: A good quality beef broth makes a noticeable difference — homemade or store-bought, just avoid the low-sodium bland stuff.

How to Serve Classic French Onion Soup Recipe

Garnishes

I always keep garnishes simple with this soup — the melty Gruyère and parmesan on top are perfect on their own. Sometimes I sprinkle a hint of fresh thyme or cracked black pepper for brightness at the end. A little fresh parsley can also add a pop of color if you like.

Side Dishes

Classic French onion soup is quite filling, so I usually pair it with something light like a crisp green salad dressed with lemon vinaigrette or roasted seasonal vegetables. A crusty fresh baguette for extra dipping never hurts either.

Creative Ways to Present

For special occasions, I like serving the soup in mini cast iron skillets or rustic crocks — it makes the cheesy top feel extra indulgent. You can even turn it into a fun appetizer by serving individual mini portions with a single toasted crouton and cheese bubbling on top.

Make Ahead and Storage

Storing Leftovers

If you end up with leftovers (which can be a rare treat in my house!), keep the soup and toasted baguette slices separate in airtight containers in the fridge. This keeps the bread from getting soggy. The soup stays great for up to 3 days.

Freezing

I’ve frozen the soup base successfully — just cool it completely and freeze in airtight containers. When you’re ready to eat, thaw overnight in the fridge, reheat gently on the stove, and add freshly toasted baguette and cheese before serving. Avoid freezing the bread or cheese topping to keep textures spot on.

Reheating

Reheat your leftover soup slowly on the stovetop over low heat, stirring occasionally. Then, toast fresh baguette slices, add the cheese, and broil as you did the first time. This fresh broil step is essential to revive that amazing melted cheesy crust.

Frequently Asked Questions:

Can I make Classic French Onion Soup Recipe vegetarian?

Absolutely! Swap the beef broth for a rich vegetable broth or mushroom broth. Skip the sherry or use a vegetarian-friendly substitute. The caramelized onions still create that deep flavor foundation.

What’s the best cheese for French onion soup?

Gruyère cheese is traditional because it melts beautifully and has a nutty, slightly sweet taste. Emmental or provolone are good alternatives, and you can add a touch of parmesan for sharpness.

How long does it take to caramelize onions properly?

It typically takes 20 to 30 minutes of slow cooking over medium-low heat to get onions to a rich golden brown. Stirring every few minutes prevents burning and ensures even cooking.

Can I prepare this soup ahead of time?

Yes! You can make the soup base a day or two in advance, store it in the fridge, and then reheat and finish with toasted bread and cheese just before serving for the best quality.

Final Thoughts

This Classic French Onion Soup Recipe has become my go-to when I want something both comforting and impressive, without fuss. The sweet, slow-cooked onions combined with a savory broth and that bubbly cheese topping just never fails to hit the spot. Trust me, once you master this recipe, you’ll find yourself craving it time and again, just like I do!