French Onion Soup

The first time I attempted French onion soup, I lived in a tiny apartment with paper thin walls and a kitchen that could barely fit two people. My neighbor, an elderly French woman, knocked on my door when she smelled the onions caramelizing and told me I was taking too long. She taught me that the secret was patience and heat control not rushing the onions into submission. That afternoon changed how I approached slow cooking forever.

I made this soup during a snowstorm last winter when my friends were stranded at my house unexpectedly. We sat around the table watching the cheese bubble and brown under the broiler, steam rising from each bowl in the cold kitchen. Something about watching snow fall outside while eating this warm, rich soup made the afternoon feel magical.

Ingredients

• 4 large yellow onions, thinly sliced: Yellow onions become sweet and mellow when caramelized, building the soups foundation
• 2 large leeks, white and light green parts only, cleaned and thinly sliced: Leeks add a subtle, sophisticated sweetness that regular onions lack
• 3 shallots, thinly sliced: These bring a gentle aromatic depth that ties the onion flavors together
• 3 garlic cloves, minced: Add these late so they do not burn and become bitter
• 3 tablespoons unsalted butter: Butter gives the onions richness and helps them caramelize evenly
• 2 tablespoons olive oil: The oil prevents the butter from burning over the long cooking time
• 8 cups high-quality beef broth: A good broth makes all the difference since the onions are the star
• 1 tablespoon Worcestershire sauce: This adds an umami depth that makes the soup taste like it simmered all day
• 2 teaspoons soy sauce: Another umami booster that enhances the savory notes
• 1/2 cup dry white wine: Use something you would drink because the flavor really comes through
• 2 teaspoons fresh thyme leaves or 1 teaspoon dried: Thyme pairs perfectly with caramelized onions
• 1 bay leaf: A classic French addition that adds subtle herbal notes
• 1 baguette, sliced into 1/2-inch rounds: Day old bread actually works better because it holds up under the broth and cheese
• 2 cups Gruyère cheese, grated: Gruyère melts beautifully and adds a nutty, complex flavor
• 1/2 cup Parmesan cheese, grated: Optional but adds a salty, savory punch
• Salt and freshly ground black pepper: Taste at the end since the cheese and broth are already salty

Instructions

Melt the butter and olive oil together:

Heat both in a large heavy bottomed pot or Dutch oven over medium heat until the butter foams

Add the alliums:

Toss in the onions, leeks, and shallots, stir well to coat them in the fat

Caramelize slowly:

Cook over medium heat, stirring frequently, for 35 to 40 minutes until the vegetables are very soft and deep golden brown

Add the garlic:

Stir in the minced garlic and cook for just 2 minutes until fragrant

Deglaze the pot:

Pour in the white wine and scrape up any browned bits stuck to the bottom

Add the broth and aromatics:

Pour in the beef broth, Worcestershire, soy sauce, thyme, and bay leaf, then bring to a gentle simmer

Simmer the soup:

Reduce heat to low and cook uncovered for 30 minutes, stirring occasionally to meld the flavors

Season and finish:

Taste and add salt and pepper as needed, then remove the bay leaf

Prepare the bread:

Preheat your oven broiler and arrange baguette slices on a baking sheet

Toast the bread:

Broil the slices for 1 to 2 minutes per side until golden and crisp

Assemble the bowls:

Ladle hot soup into oven safe bowls and top each with toasted baguette slices

Add the cheese:

Sprinkle Gruyère generously over each bowl, adding Parmesan if you like

Melt and brown:

Place bowls under the broiler for 3 to 5 minutes until the cheese is melted and bubbling

Serve immediately:

Garnish with fresh thyme sprigs if you like and enjoy while piping hot

Save

This recipe became my go to for sick friends and cold winter nights. There is something about the ritual of spooning that bubbling, cheesy topped soup that makes people feel cared for even before they take the first bite.

Choosing Your Alliums

Using three different types of onions might seem excessive but each brings something unique. Yellow onions provide the backbone sweetness, leeks contribute a sophisticated mild flavor, and shallots add a delicate aromatic quality that rounds everything out.

The Broth Matters

I have tested this with various store bought broths and homemade makes the biggest difference. If you are using store bought, look for one with minimal ingredients and a deep, beefy flavor. The better your broth, the better your final soup will taste.

Make Ahead Magic

This soup actually tastes better the next day once the flavors have had time to meld. I often make a big batch on Sunday and keep it in the refrigerator. When we are ready to eat, I just reheat, toast fresh bread, and broil the cheese.

• The soup base freezes beautifully for up to three months
• Never freeze it with the bread and cheese already added
• Thaw overnight in the refrigerator before reheating

Save

There is nothing quite like breaking through that crispy, cheesy crust into the hot soup below. It is the kind of meal that makes you slow down and savor every spoonful.

Recipe FAQs

→ How do I achieve perfectly caramelized onions?

Cook sliced onions, leeks, and shallots over medium heat with butter and olive oil for 35-40 minutes, stirring frequently. They should turn deep golden brown and very soft—don't rush this step as it builds the soup's signature sweetness and depth.

→ Can I make this vegetarian?

Yes. Substitute high-quality vegetable broth for beef broth and use a vegetarian Worcestershire sauce alternative or omit it entirely. The flavor will remain satisfyingly rich and savory.

→ What type of cheese works best?

Traditional Gruyère offers the best melting qualities and nutty flavor. Swiss or Emmental make excellent alternatives. For extra depth, add Parmesan to the cheese mix before broiling.

→ Can I prepare this soup in advance?

The soup base actually improves after 1-2 days in the refrigerator as flavors meld. Prepare through step 5, cool, and store. Reheat gently, then add fresh bread and cheese just before serving for the best texture.

→ What's the secret to the perfect cheesy top?

Toast baguette slices under the broiler first to create a sturdy base that won't get soggy. Use ample Gruyère and broil until melted and bubbly with golden spots—watch closely as it can brown quickly.

→ How thin should I slice the onions?

Slice onions, leeks, and shallots into thin, even rounds about 1/8 inch thick. This ensures even cooking and helps the alliums break down properly during the long caramelization process.