If you’ve been searching for a simple, foolproof French Onion Soup, you’re in the right place! This is one of my absolute favorites—it’s incredibly comforting and rich in flavor. Plus, it’s surprisingly good for you; those beautifully caramelized onions are loaded with essential nutrients like Vitamin C, potassium, and manganese.

The finishing touch is what really seals the deal. A generous layer of shredded mozzarella and Swiss (or Gruyère) that melts into a golden, bubbly crust in the oven. Add homemade garlic-thyme croutons and suddenly this soup is on the next level. That said, if you’re not in the mood to make croutons from scratch, store-bought works just fine. It still tastes amazing! You can also sub out the beef stock and use vegetable stock to make this French Onion Soup vegetarian. Want more French onion flavours? Try my French Onion Dip, French Onion Potato Skins, or French Onion Chicken & Orzo.

😍 Why You’ll Love This Easy French Onion Soup

Classic comfort: All the deep, rich flavour of traditional French onion soup without complicated steps or hard-to-find ingredients.
Big onion flavour: Slowly caramelized onions create that signature sweet-savory depth that makes this soup so satisfying.
Cheesy, golden finish: A generous layer of mozzarella and Swiss melts into a bubbly, crisp topping.
Adaptable: Use beef or vegetable stock, white or red wine, or even skip the wine altogether — it still turns out delicious.

🧅 Ingredients To Make This Easy French Onion Soup

Yellow onions: thinly sliced and slowly caramelized until sweet, jammy, and deeply golden, they create the signature rich base of classic French onion soup.
Olive oil & butter: gives you the best of both worlds. Olive oil prevents burning while butter adds richness.
Garlic: adds warmth and depth once the onions are fully caramelized.
Sugar: just a small amount helps the onions caramelize properly and enhances their natural sweetness.
Tomato paste: a subtle but important addition that deepens the colour and adds umami without making the soup taste tomato-forward.

White wine: used to deglaze the pot, lifting all those caramelized bits off the bottom and adding brightness to balance the rich onions.
Worcestershire sauce: brings depth and complexity. It’s a flavour booster that makes the soup taste fuller.
Beef stock: forms the main base of the soup, giving it that classic, robust French onion flavour. (Vegetable stock works great too if you want to keep it vegetarian.)
Mozzarella: melts easily and creates that stretchy, gooey layer under the top cheese.
Gruyère or Swiss cheese: the classic French onion topping — nutty, salty, and perfect for broiling into a golden crust.

For the croutons:

Day-old baguette: crisps up in the oven and holds its shape once it hits the broth.
Olive oil: helps the croutons turn golden and crunchy without drying out.
Garlic powder: adds flavour.
Fresh thyme: brings a fresh, earthy note that ties in perfectly with the onions and cheese.

✔ How To Make This French Onion Soup

To make this easy french onion soup recipe, start by preheating your oven to 400 °F. Begin by chopping your baguette into half inch cubes and place in a medium sized bowl. Add all of your crouton ingredients and mix to combine. Taste here to adjust for any seasonings.

If using store-bought croutons simply skip this step. Arrange bread cubes on a baking sheet. Bake for 7–10 minutes until golden brown. Remove and set aside.

Thinly slice your onions, and set aside until ready to use. To a large pot, add your olive oil and butter and set to low/medium heat. Once hot, add your onions. Sauté onions on low-medium heat for 30 minutes. Stir in the sugar and continue cooking for another 15–30 minutes, stirring frequently, until the onions are deeply browned and fully caramelized.

🤝 Sammy’s Tips for Easy French Onion Soup

• If onions brown too quickly, stir in 1–2 tablespoons of water to deglaze the pan and regulate the temperature.
• Slice your onions pretty fine! You don’t want big thick chunks of onions in your soup so try to slice them as thin as you can.
• Caramelize those onions! If you notice that your onions are absorbing too much of the liquid and appear to be burning, feel free to add a little bit of extra butter or olive oil to the pot to re hydrate them to continue caramelizing.
• You can top with whatever type of cheese that you like! Traditional French onion soup uses gruyere, although I prefer the flavour of swiss so that’s what I use in my recipe. They are pretty similar in flavour, although gruyere is a bit stronger.
• When you top your soup with croutons, just be aware that they will absorb a lot of that broth, so don’t add as many croutons as you think if you are looking to have a more brothy soup base.

Once the onions are caramelized and golden in colour, add your garlic, salt, fresh thyme and sauté for an additional 2-3 minutes. Add your tomato paste and cook for 2 to 3 minutes or until the tomato paste turns a deep red color.

Deglaze with your white wine and simmer for 2 to 3 minutes, just until the wine reduces by half. Add your worcestershire and beef stock and stir to combine. Taste here to see if you need any additional seasonings.

Then, bring the soup to a simmer and allow to simmer for 5-7 minutes. Turn the heat off and ladle your soup into your oven safe bowls.

Place toasted croutons into each ramekin/bowl then evenly distribute the mozzarella over the croutons and top each bowl with a large slice of Gruyère or Swiss cheese.

Bake in a 400 °F degree oven for 5 minutes, or until the cheese has fully melted.

🗒 Variations

Herb-forward: Stir in fresh thyme or a bay leaf while the soup simmers to lean into those classic French onion flavours even more.
More indulgent: Double up on the cheese topping or add a mix of Swiss and Gruyère for an extra-thick, bubbly crust.

🗒 Substitutions

Stock swap: Use vegetable stock in place of beef stock for a vegetarian-friendly version that’s still rich and comforting.
Cheese choices: Gruyère, Swiss, provolone, or even a mild white cheddar all melt great on top.
Bread options: No baguette? Use sourdough, ciabatta, or even thick-cut sandwich bread for the croutons. Just toast until crisp.

🍴 Leftovers? Lucky You.

This easy French onion soup keeps surprisingly well. Store any leftovers in an airtight container in the fridge for up to 3–4 days. When reheating, warm it gently on the stovetop over low heat. If it’s thickened in the fridge, just add a splash of stock or water to loosen it up. For best results, add fresh croutons and cheese just before serving — they’re much better toasted and melted fresh than reheated.

🤔 FAQ’S

👩🏻‍🍳 Hungry For More? 

If you loved this Easy French Onion Soup recipe, then make sure to check out a few of my other soups you may also love:

• Chicken Poblano Soup
• Easy Chicken Noodle Soup
• Stuffed Pepper Soup Recipe
• Potato and Leek Soup
• Sausage Tortellini Soup

💌 Let’s Stay Connected

Keep in touch with me on Instagram, TikTok, Facebook, and Pinterest! If you do make this easy french onion soup recipe (or any recipe of mine) don’t forget to leave a review.