Classic French Onion Soup

This French Onion Soup is a cozy, classic dish that combines sweet, buttery caramelized onions with a rich, savory broth and melted cheesy bread on top. It is perfect for slow weekend dinners or special occasions when you want something deeply flavorful and comforting. The layers of texture and taste make it feel like a warm hug in a bowl.

I first tried this recipe on a chilly evening and was hooked by how the melting cheese and broth warmed me from the inside out. Now it’s one of my go to dishes when I want something classic that impresses friends.

Ingredients

• Olive oil: for sautéing, choose extra virgin for best flavor
• Unsalted butter: enriches the onions as they soften
• Yellow onions: the heart of the soup, offering sweetness and a bright but mellow flavor
• Sugar: to aid in caramelizing and bringing out onion sweetness
• Salt: seasons the onions and broth
• All purpose flour: helps thicken the soup without overpowering it
• Broth: choose low sodium beef broth for controlled seasoning and depth
• Red wine: dry varieties like Pinot Noir or Merlot bring acidity and complexity
• Bay leaves and thyme: fresh herbs add a subtle aromatic background
• Cognac: adds a touch of warmth and depth but can be substituted with brandy or skipped
• French baguette: crusty bread to soak in the soup and hold the melty cheese
• Gruyere cheese: essential for its creaminess and melting quality
• Parmesan cheese: adds a nutty sharpness that enhances the topping

Instructions

Caramelize Onions:

Start by heating the olive oil and two tablespoons of butter in a heavy pot over medium heat. Once the butter melts, add the thinly sliced onions and stir to coat them evenly. Cover the pot and let the onions cook gently for 20 minutes, stirring occasionally so they don’t stick. This step softens the onions and starts their natural sweetness.

Finish Caramelizing:

Remove the lid and sprinkle sugar and salt over the onions. Continue cooking uncovered for about 40 minutes, stirring every few minutes. Watch as the onions turn a deep golden brown and develop a rich, sweet aroma. This slow caramelization is what gives the soup its signature flavor.

Make a Roux:

Add the flour and one more tablespoon of butter to the pot with the onions. Stir constantly and cook for about 2 to 3 minutes. This cooks out the raw flour taste and slightly thickens the base of the soup.

Deglaze the Pot:

Pour in one cup of the beef broth and stir to loosen any flavorful brown bits stuck to the bottom. Let this cook for a minute so the liquid reduces slightly and incorporates those caramelized flavors back into the soup base.

Add Broth, Wine, and Herbs:

Pour in the remaining broth and the red wine. Toss in the bay leaves and thyme sprigs. Stir gently and bring the soup to a boil. Then lower the heat and let it simmer uncovered for about 30 minutes to meld the flavors together.

Season and Add Cognac:

Remove the bay leaves and thyme sprigs. Taste the soup and add salt and pepper as needed. Stir in the cognac for a subtle warming note that rounds out the flavor.

Prepare the Bread and Cheese:

If you like, drizzle the baguette slices lightly with olive oil and toast them under a broiler for about 30 seconds to 1 minute per side until golden and crisp. Spoon about a cup of Gruyere cheese over the soup in your oven safe pot, then place the toasted bread over the cheese. Top the bread with the remaining Gruyere and sprinkle Parmesan on top.

Melt the Cheese:

Preheat your oven to 350 degrees Fahrenheit. Transfer the pot to the oven and bake for 20 to 25 minutes until the cheese is bubbly and lightly browned. Serve hot, scooping generous portions of cheesy bread and soup into bowls.

One family moment I treasure is passing down this recipe to my kids, who now insist on helping with the caramelization because they love the smell and taste so much.

Storage Tips

French Onion Soup stores beautifully covered in the refrigerator for three to four days. Let it cool completely before sealing it airtight. To freeze, use heavy duty freezer bags or containers and label the date. Thaw overnight in the fridge before reheating gently on the stove or in the microwave to avoid cheese clumping.

Ingredient Substitutions

You can substitute shallots or a mix of yellow and sweet onions for a slightly different flavor profile. For a vegetarian version, use vegetable broth and skip the cognac or replace it with a splash of balsamic vinegar. Try Swiss cheese instead of Gruyere if that’s what you have handy, though the texture and flavor will vary.

Serving Suggestions

Serve French Onion Soup with a crisp green salad or roasted vegetables for a complete meal. It also pairs beautifully with a glass of red wine, echoing the notes used in the soup. For an elegant twist, add a sprinkle of fresh herbs like parsley just before serving.

Enjoy this classic French Onion Soup for cozy dinners and special occasions. It rewards patience with deeply savory, comforting results.

Common Questions About Recipes

→ What type of onions work best for this dish?

Yellow onions are ideal for their natural sweetness and rich flavor, but shallots can be used for added depth and brightness.

→ How do I caramelize onions properly?

Cook sliced onions slowly in butter and olive oil over medium heat, stirring often, until they turn deeply golden and sweet, about 60 minutes in total.

→ Can I substitute the red wine?

Yes, dry red wines like Pinot Noir, Merlot, or Côtes du Rhône enhance the flavor, but you may omit or replace with a non-alcoholic stock if desired.

→ Why add cognac to the broth?

Cognac adds a rich, warm depth and complexity that complements the sweetness of caramelized onions and herbs.

→ What cheeses are recommended for melting on top?

Gruyere is preferred for its smooth melt and rich flavor, often combined with Parmesan for a sharp, savory finish.

→ How should the bread be prepared before adding?

Lightly toast the French baguette slices with a sprinkle of olive oil under the broiler until golden to add texture and prevent sogginess.