French Onion Soup – A Cozy, Caramelized Classic

French onion soup is comfort in a bowl: sweet, slow-cooked onions, savory broth, and a golden lid of melty cheese over toasted bread. It’s simple food with big flavor, made from humble ingredients that turn into something special. If you love rich, deep flavors, this is the kind of soup that makes you stop and savor every spoonful.

It’s perfect for a chilly evening, a dinner party starter, or a treat-yourself lunch with a crisp salad on the side.

French Onion Soup - A Cozy, Caramelized Classic

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Prep Time 15 minutes mins

Cook Time 1 hour hr

Total Time 1 hour hr 15 minutes mins

Servings 6 servings

Ingredients

  

• 3 pounds yellow onions, thinly sliced (about 6–8 medium onions)
• 3 tablespoons unsalted butter
• 1 tablespoon olive oil
• 1 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon freshly ground black pepper
• 1 teaspoon sugar (optional, helps with caramelization)
• 2 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 1/2 cup dry white wine or dry sherry (optional but recommended)
• 6 cups beef broth (or a mix of beef and chicken broth). For vegetarian, use a rich vegetable broth.
• 2 teaspoons Worcestershire sauce (optional; skip for vegetarian)
• 2 sprigs fresh thyme or 1/2 teaspoon dried thyme
• 1 bay leaf
• 1 baguette, sliced into 1/2-inch rounds
• 2 cups grated Gruyère or Emmental (or a blend), plus a little Parmesan if you like

Instructions

 

• Prep the onions: Peel and slice the onions thinly from root to tip. Keep the slices even so they cook consistently.
• Start the caramelization: In a large heavy pot or Dutch oven, melt the butter with the olive oil over medium heat. Add the onions, salt, and sugar (if using). Toss to coat.
• Cook low and slow: Reduce the heat to medium-low and cook, stirring every few minutes. Scrape the bottom often. This step takes 40–60 minutes. The onions should go from translucent to golden to deep brown. If they start to scorch, lower the heat and add a splash of water to loosen the fond.
• Add garlic and flour: Stir in the garlic and cook for 30 seconds until fragrant. Sprinkle in the flour and cook for 1–2 minutes to remove the raw taste. The onions will look a bit pasty—this is good.
• Deglaze with wine: Pour in the wine (if using) and scrape up all the browned bits. Let it bubble for 2–3 minutes to reduce slightly.
• Simmer the soup: Add the broth, Worcestershire (if using), thyme, and bay leaf. Bring to a gentle simmer and cook for 20–30 minutes. Taste and adjust salt and pepper.
• Toast the bread: While the soup simmers, toast the baguette slices on a sheet pan at 375°F (190°C) until crisp and lightly golden, about 8–10 minutes. This keeps them from getting soggy.
• Assemble for broiling: Ladle the soup into oven-safe bowls set on a sheet pan. Top each with 1–2 baguette slices and a generous mound of grated cheese.
• Broil to finish: Place under the broiler for 2–4 minutes, watching closely, until the cheese melts and browns in spots. Let cool slightly before serving.
• Serve: Add a crack of pepper and a few thyme leaves on top. The cheese will be stretchy, the bread will be soaked just enough, and the broth will be deeply savory.

Why This Recipe Works

This recipe is all about technique, not fancy ingredients. The magic comes from slowly caramelizing the onions until they’re jammy and sweet. A splash of wine helps lift the browned bits from the pan, adding complexity.

Using good beef or rich vegetable broth makes the soup taste full and round. Finally, toasting the bread and broiling it with Gruyère or Emmental creates that irresistible cheesy crust.

Ingredients

• 3 pounds yellow onions, thinly sliced (about 6–8 medium onions)
• 3 tablespoons unsalted butter
• 1 tablespoon olive oil
• 1 teaspoon kosher salt, plus more to taste
• 1/2 teaspoon freshly ground black pepper
• 1 teaspoon sugar (optional, helps with caramelization)
• 2 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 1/2 cup dry white wine or dry sherry (optional but recommended)
• 6 cups beef broth (or a mix of beef and chicken broth). For vegetarian, use a rich vegetable broth.
• 2 teaspoons Worcestershire sauce (optional; skip for vegetarian)
• 2 sprigs fresh thyme or 1/2 teaspoon dried thyme
• 1 bay leaf
• 1 baguette, sliced into 1/2-inch rounds
• 2 cups grated Gruyère or Emmental (or a blend), plus a little Parmesan if you like

How to Make It

1. Prep the onions: Peel and slice the onions thinly from root to tip.

   Keep the slices even so they cook consistently.

2. Start the caramelization: In a large heavy pot or Dutch oven, melt the butter with the olive oil over medium heat. Add the onions, salt, and sugar (if using). Toss to coat.
3. Cook low and slow: Reduce the heat to medium-low and cook, stirring every few minutes.

   Scrape the bottom often. This step takes 40–60 minutes. The onions should go from translucent to golden to deep brown.

   If they start to scorch, lower the heat and add a splash of water to loosen the fond.

4. Add garlic and flour: Stir in the garlic and cook for 30 seconds until fragrant. Sprinkle in the flour and cook for 1–2 minutes to remove the raw taste. The onions will look a bit pasty—this is good.
5. Deglaze with wine: Pour in the wine (if using) and scrape up all the browned bits.

   Let it bubble for 2–3 minutes to reduce slightly.

6. Simmer the soup: Add the broth, Worcestershire (if using), thyme, and bay leaf. Bring to a gentle simmer and cook for 20–30 minutes. Taste and adjust salt and pepper.
7. Toast the bread: While the soup simmers, toast the baguette slices on a sheet pan at 375°F (190°C) until crisp and lightly golden, about 8–10 minutes.

   This keeps them from getting soggy.

8. Assemble for broiling: Ladle the soup into oven-safe bowls set on a sheet pan. Top each with 1–2 baguette slices and a generous mound of grated cheese.
9. Broil to finish: Place under the broiler for 2–4 minutes, watching closely, until the cheese melts and browns in spots. Let cool slightly before serving.
10. Serve: Add a crack of pepper and a few thyme leaves on top.

    The cheese will be stretchy, the bread will be soaked just enough, and the broth will be deeply savory.

How to Store

• Refrigerate: Store the soup (without bread and cheese) in an airtight container for up to 4 days. Reheat gently on the stove until steaming.
• Freeze: The soup base freezes well for up to 3 months. Cool completely, portion, and freeze.

  Thaw overnight in the fridge before reheating.

• Bread and cheese: Keep toasted bread at room temperature in a container for 1–2 days. Add cheese and broil just before serving.
• Make-ahead tip: Caramelize onions in advance and refrigerate for up to 5 days or freeze in portions. This saves time later.

Benefits of This Recipe

• Budget-friendly: Onions, broth, and bread are simple, affordable ingredients that deliver big flavor.
• Deep flavor from technique: Caramelization builds sweetness and complexity without needing lots of extras.
• Flexible: Works with beef, chicken, or rich vegetable broth.

  Cheese and bread can be adapted to what you have.

• Make-ahead friendly: The soup base tastes even better the next day, and it freezes well.
• Comfort factor: Warm, cheesy, and aromatic—perfect for a cozy meal.

What Not to Do

• Don’t rush the onions: High heat will burn them before they caramelize. Low and slow is the key.
• Don’t skip deglazing: Those browned bits on the pan are pure flavor. Wine or a splash of broth will bring them into the soup.
• Don’t use weak broth: Thin, bland broth leads to flat soup.

  Use a quality stock or simmer store-bought broth with a bay leaf and thyme to boost it.

• Don’t add bread too early: If you simmer the bread in the soup, it gets mushy. Toast and broil it at the end.
• Don’t over-salt early: The soup reduces as it simmers. Season gradually and adjust at the end.

Recipe Variations

• Vegetarian: Use a rich vegetable broth.

  Add a splash of soy sauce or a dash of miso for depth. Skip Worcestershire or choose a vegetarian version.

• Classic Paris bistro style: Use mostly beef broth, dry white wine, and Gruyère. Keep the seasoning simple and clean.
• Sherry-forward: Swap the wine for dry sherry and finish with a small pat of butter for a silky finish.
• Cheese blend: Combine Gruyère with a little Comté, Emmental, or even a bit of Parmesan for extra nuttiness.
• Gluten-free: Use gluten-free bread and a gluten-free thickener (or skip the flour and reduce the soup slightly longer).
• Onion mix: Blend yellow onions with a few red or sweet onions for layered flavor.

  A shallot or two adds a gentle bite.

FAQ

How long should I caramelize the onions?

Plan on 45–60 minutes over medium-low heat. You’re looking for deep brown color and jammy texture, not just soft onions. If they’re browning too fast, lower the heat and add a splash of water to control the process.

What’s the best cheese for French onion soup?

Gruyère is the classic choice because it melts beautifully and has a nutty flavor.

Emmental, Comté, or a Gruyère-Parmesan blend also work well. Avoid overly oily cheeses that don’t brown nicely.

Can I make this without alcohol?

Yes. Skip the wine and deglaze with a bit of broth plus 1–2 teaspoons of apple cider vinegar for brightness.

The vinegar adds a subtle lift that keeps the soup from tasting flat.

Do I have to use flour?

No. Flour gives a slightly fuller body, but you can leave it out. Simply simmer the soup a bit longer to reduce and concentrate the broth.

What bread works best?

Baguette slices are ideal because they’re sturdy and toast up well.

Sourdough rounds or country bread also work. Make sure the bread is toasted before broiling so it holds its shape under the cheese.

Can I use red wine instead of white?

Yes, but use a light hand. Red wine brings a deeper, more robust flavor.

Add 1/4 to 1/3 cup and taste as you go so it doesn’t overpower the onions.

Why is my soup bitter?

Bitterness usually comes from burned onions. Keep the heat moderate, stir regularly, and add a splash of water when needed to loosen stuck bits and control browning.

How can I make the broth taste richer?

Simmer the finished soup with an extra bay leaf and thyme for 10 minutes, or add a teaspoon of soy sauce or a dab of miso. A small pat of butter at the end adds body and sheen.

In Conclusion

French onion soup proves that simple ingredients can be truly special with the right technique.

Take your time with the onions, use a solid broth, and finish with a crisp lid of toasted bread and cheese. It’s cozy, satisfying, and timeless—exactly the kind of dish you’ll return to whenever you want a warm, hearty bowl of comfort.