French Onion Soup with Croutons Recipe

This French onion soup with croutons is built on one slow job: turning four large onions into a soft, deeply golden pile. Once that is done, the rest comes together fast. Garlic, thyme, a spoonful of flour, optional white wine and beef broth simmer into a savory base, then broth-soaked croutons and a thick layer of cheese go on top and under the broiler. The cheese melts, bubbles and browns, and you crack through it with a spoon. Plan on roughly 1 hour 30 minutes from the first onion slice to the first bowl, with most of that time spent stirring now and then.

Why You’ll Like This French Onion Soup

The ingredient list is short and nothing on it is hard to find. The flavor comes from patience, not from extra steps. Onions cooked slowly in butter and olive oil turn sweet and jammy, and the beef broth carries that richness through every spoonful. Croutons take the place of a sliced baguette, so there is no toasting bread separately.

• Simple pantry ingredients: onions, butter, broth, flour, a little thyme and a bay leaf do most of the work.
• Wine is optional: the soup works with or without it.
• Flexible cheese: Gruyère, Swiss or provolone all melt well on top.
• Cooks mostly unattended: after the onions are going, you only need to stir from time to time.

Ingredients for French Onion Soup with Croutons

• 4 large yellow onions, thinly sliced
• 3 tbsp butter
• 1 tbsp olive oil
• 2 cloves garlic, minced
• 1 tsp dried thyme
• 1/2 tsp black pepper
• 1/2 tsp salt, plus more to taste
• 1 tbsp Worcestershire sauce
• 1 tbsp flour
• 6 cups beef broth
• 1/2 cup dry white wine (optional)
• 1 bay leaf
• 2 to 3 cups seasoned croutons
• 2 cups shredded Gruyère, Swiss or provolone cheese

Ingredient Notes

Onions: Yellow onions are the right choice here. Slice them thinly and as evenly as you can so they soften and brown at the same pace. The pile looks huge at first and shrinks a lot as it cooks.

Beef broth: Since broth is the main liquid, its flavor shows up in the finished bowl. Use one you enjoy drinking warm, and taste before adding extra salt at the end.

White wine: A dry white works. Skipping it is fine, and the soup will simply taste a little less tangy.

Cheese: Gruyère gives a nutty, savory flavor, Swiss is milder, and provolone melts into a smooth, stretchy layer. Shred it yourself from a block if you can, since it melts more evenly than most pre-shredded cheese.

Croutons: Seasoned croutons add flavor as they soften in the broth. Choose a sturdy kind that won’t dissolve right away.

How to Make French Onion Soup with Croutons

Step by Step

1. Start the onions. Melt the butter and olive oil in a large pot over medium-low heat. Add the sliced onions and a pinch of salt.
2. Caramelize. Cook the onions for 35 to 45 minutes, stirring occasionally, until they are soft, deeply golden brown and caramelized.
3. Add garlic and thyme. Stir in the garlic and thyme and cook for about 1 minute.
4. Add the flour. Sprinkle the flour over the onions and stir well. Cook for another minute.
5. Deglaze with wine, if using. Pour in the white wine and scrape up any browned bits from the bottom of the pot. Simmer for 2 to 3 minutes.
6. Build the broth. Add the beef broth, Worcestershire sauce, black pepper and bay leaf. Bring to a gentle boil, then reduce the heat and simmer uncovered for 20 to 30 minutes.
7. Season. Remove the bay leaf. Taste, and add more salt and pepper if needed. The recipe uses 1/2 tsp salt, plus more to taste.
8. Fill the bowls. Ladle the soup into oven-safe bowls. Add a layer of croutons on top, then gently press or dip them into the hot soup so they soak up some broth and soften. Leave them partly floating.
9. Add the cheese. Cover the croutons completely with the shredded cheese.
10. Broil. Place the bowls under the broiler for 2 to 5 minutes. Watch closely until the cheese is melted, bubbly and golden brown.
11. Rest and serve. Carefully take the bowls out of the oven and let them sit for a few minutes before serving.

Oven and Broiler Safety

Only use bowls that are labeled oven-safe and rated for broiler heat. Regular bowls can crack under direct heat. Set the bowls on a baking sheet so they are easy to move, and use dry oven mitts when you lift them. The bowls and the soup inside will be extremely hot, so give them a few minutes to settle before anyone picks up a spoon. Stay at the oven the entire time, because cheese can go from golden to burnt within seconds.

Tips for the Best French Onion Soup

Keep the Heat Low for the Onions

Medium-low heat is the whole trick. If the onions start to scorch before they soften, turn the heat down. Stir occasionally and scrape the bottom of the pot as the color deepens. The 35 to 45 minutes is not something to rush, and you will see the onions go from pale to amber to a rich golden brown.

Don’t Skip the Pinch of Salt at the Start

Salt added with the onions helps draw out their moisture, which makes the cooking easier. Keep it to a pinch at this point and do your real seasoning after the broth has simmered.

Scrape the Pot

The browned bits stuck to the bottom hold a lot of flavor. If you use wine, that is the moment to scrape them loose. If you skip the wine, a splash of the broth will help you do the same.

Press the Croutons Into the Soup

Dipping the croutons into the hot soup softens them and keeps the cheese from sliding off. Leave part of each crouton above the surface so the cheese has something to sit on.

Cover the Croutons Completely With Cheese

A full layer of cheese melts into one bubbly cap and browns evenly. Let it run slightly over the edge of the bowl if you like crisp, browned cheese along the rim.

What to Serve With French Onion Soup

A crisp green salad with a sharp vinaigrette pairs well with the rich, cheesy bowl. A sandwich such as ham and cheese or turkey also makes a good side, and extra croutons or crusty bread work if you want more to dunk.

Variations

• Different cheese: Use Gruyère, Swiss or provolone, or mix two of them for a blend of flavors.
• No wine: Leave out the white wine and go straight from the flour to the broth.

Storage and Reheating

Refrigerator: Store the soup base without the croutons or cheese in an airtight container in the refrigerator. It keeps for up to 3 days.

Reheating: Warm the soup in a pot over medium-low heat until steaming. Then ladle it into oven-safe bowls, add fresh croutons and cheese, and broil again as in the recipe. Croutons that have already been soaked turn very soft, so it is better to add new ones.

Freezing: You can freeze the soup base without the croutons and cheese in a freezer-safe container for up to 2 months. Thaw it in the refrigerator overnight, reheat it on the stove and finish it under the broiler.

Frequently Asked Questions

How long does it take to caramelize the onions?

Plan on 35 to 45 minutes over medium-low heat, stirring occasionally. They are ready when they are soft and deeply golden brown. Lower heat takes longer but is gentler on the onions.

Can I make French onion soup without wine?

Yes. The wine is optional. Skip it and add the beef broth right after the flour has cooked for a minute. Scrape the bottom of the pot as you pour in the broth.

What bowls can I use under the broiler?

Use only oven-safe bowls that are made to take broiler heat, such as ceramic crocks. Check what they are rated for before use, put them on a baking sheet and handle them with dry oven mitts.

Which cheese is best for French onion soup?

Gruyère, Swiss and provolone all work. Gruyère has the nuttiest flavor, Swiss is milder and provolone melts into a smooth, stretchy top. Use 2 cups, shredded, and cover the croutons completely.