French Onion Soup is a classic dish that features sweet, caramelized onions simmered in a rich beef broth and topped with a golden, bubbly layer of melted cheese. The crispy, toasted bread floating on top soaks up the flavorful broth, making each spoonful a delightful mix of textures and tastes. It’s a cozy soup that feels just right on a chilly day.
I love making French Onion Soup when I want something simple but special. Slowly cooking the onions until they turn beautifully brown takes some time, but the result is so worth it. I always find that stirring gently and letting the aroma fill the kitchen is one of the best parts of the process—it makes me look forward to the meal even more.
My favorite way to enjoy this soup is straight from the oven, when the cheese is still gooey and warm. Sometimes I like to add a little extra crusty bread on the side to dunk into the bowl. This soup always brings back memories of family dinners and casual nights with friends gathered around the table, sharing good food and conversation.
Key Ingredients & Substitutions
Onions: Yellow onions are best because they become sweet and tender when caramelized. If you can’t find yellow, sweet onions or even Vidalia can work, though the flavor may be a bit milder.
Broth: Beef broth gives the traditional deep flavor. For a lighter or vegetarian option, use mushroom broth or vegetable broth with a splash of soy sauce or Worcestershire sauce for depth.
Cheese: Gruyère melts beautifully and adds a nutty richness. Swiss cheese is a good substitute. Avoid very mild cheeses—they won’t brown or flavor the same.
Bread: A crusty baguette is perfect for soaking up the soup without getting soggy too fast. If baguette isn’t available, a good rustic bread or sourdough slice toasted works well.
How Do I Get Perfectly Caramelized Onions for French Onion Soup?
Caramelizing onions slowly is key to developing that sweet, deep flavor without burning. Follow these tips:
- Slice onions evenly for uniform cooking.
- Cook over medium-low heat to let sugars develop gently.
- Stir often but not constantly—enough to prevent sticking.
- Add a pinch of sugar early to encourage browning.
- Be patient—it usually takes 45-60 minutes for the best caramelization.
- If onions start to stick or burn, add a splash of water or broth to loosen and continue cooking.
Taking the time here really makes the difference between bland and rich soup!
Equipment You’ll Need
- Large heavy-bottomed pot – I like using a good Dutch oven because it heats evenly and can go from stovetop to oven.
- Sharp knife and cutting board – makes slicing onions quick and safe.
- Baking sheet – for toasting the bread slices evenly.
- Oven-safe bowls or crocks – to hold the soup under the broiler for cheese melting.
- Broiler or oven with a broil setting – for bubbly, golden cheese tops.
- Soup ladle – easy to serve individual bowls of hot soup.
Flavor Variations & Add-Ins
- For a richer flavor, add a splash of sherry or red wine when cooking the onions or in the broth.
- Use Gruyère cheese for authenticity, but Swiss, Emmental, or even cheddar can add a different twist.
- Mix in sautéed mushrooms or cooked bacon bits for extra flavor and texture.
- For a vegetarian version, swap beef broth for vegetable broth and add additional herbs like rosemary or oregano.
How to Make French Onion Soup
Ingredients You’ll Need:
For the Soup:
- 6 large yellow onions, thinly sliced
- 4 tbsp unsalted butter
- 2 tbsp olive oil
- 1 tsp salt
- 1 tsp sugar
- 4 cloves garlic, minced
- ½ cup dry white wine (optional)
- 8 cups beef broth (or a mix of beef and chicken broth)
- 2 bay leaves
- 4-5 sprigs fresh thyme
- Salt and freshly ground black pepper, to taste
For the Topping:
- 1 baguette, sliced into ½ inch thick slices
- 2 cups grated Gruyère cheese (or Swiss cheese)
- Fresh thyme sprigs, for garnish
How Much Time Will You Need?
This recipe takes about 20 minutes of prep and roughly 1.5 hours to slowly caramelize the onions. After that, it simmers for 30 minutes and requires a few minutes to toast the bread and melt the cheese. Overall, plan for about 2 hours from start to finish.
Step-by-Step Instructions:
1. Caramelize the Onions:
In a large, heavy-bottomed pot, melt the butter with olive oil over medium heat. Add the sliced onions and stir well to coat. Sprinkle with salt and sugar to help bring out the sweetness. Cook, stirring often, until the onions are golden brown and deeply caramelized, about 45 to 60 minutes. Keep an eye so they don’t burn, lowering the heat if needed.
2. Add Garlic and Wine:
Stir in the minced garlic and cook for 1 minute until fragrant. Pour in the white wine (if using), scraping the bottom of the pot with a wooden spoon to release any tasty browned bits. Let the wine reduce for 3 to 5 minutes.
3. Simmer the Soup:
Add the beef broth, bay leaves, and fresh thyme sprigs. Bring to a gentle simmer and cook uncovered for at least 30 minutes to deepen the flavors. Season with salt and freshly ground black pepper to taste. Remove the bay leaves and thyme sprigs before serving.
4. Prepare the Bread and Cheese:
While the soup simmers, preheat your oven’s broiler. Arrange the baguette slices on a baking sheet and toast them under the broiler until golden brown on both sides. Keep a close eye so they don’t burn!
5. Assemble and Broil:
Ladle the hot soup into oven-safe bowls. Place 1 or 2 toasted baguette slices on top of each bowl, then generously sprinkle with grated Gruyère cheese. Place the bowls under the broiler for 3 to 5 minutes, until the cheese melts, bubbles, and turns golden brown. Watch carefully to avoid burning.
6. Serve and Enjoy:
Garnish each bowl with fresh thyme sprigs and serve immediately. Enjoy the cozy, rich flavors of your homemade French Onion Soup with its bubbly cheese topping and crusty bread!
Can I Use Yellow Onion Substitutes?
Yes, sweet onions like Vidalia or red onions can work if yellow onions aren’t available, but the flavor might be a little milder or slightly different. Yellow onions give the best balance of sweetness and depth.
How Should I Store Leftover French Onion Soup?
Store leftovers in an airtight container in the fridge for up to 3 days. Reheat gently on the stovetop over low heat to keep the flavors fresh. For the best texture, add fresh toasted bread and cheese when reheating.
Can I Make This Soup Vegetarian?
Absolutely! Use vegetable broth instead of beef broth, and add extra herbs like rosemary or mushrooms for a richer taste. Skip the white wine or use a vegan-friendly variety to keep it fully vegetarian.
What’s the Best Bread to Use for Topping?
A crusty baguette works perfectly because it holds up well when soaked in the soup without becoming soggy too fast. If you can’t get a baguette, try a rustic sourdough or any sturdy, crusty bread.