French Onion Soup Recipe Using Canned Soup, Made Easy

French onion soup is a French bistro-style soup of tender onions in savory broth, usually served with toasted bread and melted cheese. This version uses canned French onion soup as a shortcut, then builds extra depth with slowly browned onions, broth, and a bubbling Gruyère topping.

Ingredients

2 tablespoons unsalted butter (28 g)
1 teaspoon neutral oil (5 ml)
2 large yellow onions, thinly sliced (about 450 g)
1 tablespoon dry sherry (15 ml), optional
2 cans condensed French onion soup, 10.5 ounces (298 g) each
2 cups low-sodium beef broth (480 ml)
1 cup water (240 ml), plus a little more if needed
1 teaspoon Worcestershire sauce (5 ml)
1/2 teaspoon dried thyme (about 0.5 g)
1 bay leaf
1/4 teaspoon freshly ground black pepper (about 0.5 g)
4 baguette slices, about 1/2 inch (1.3 cm) thick (about 115 g total)
1 1/2 cups shredded Gruyère cheese (about 150 g)
Salt, as needed after tasting (start with none)

Instructions

Prepare the onions and toppings. Slice the onions evenly, so they soften at roughly the same rate. Shred the Gruyère if it is not already shredded, and set out four oven-safe soup bowls if you plan to broil the finished soup. Check that the bowls are explicitly safe for broiler use; ordinary ceramic can crack under intense direct heat. If you do not have suitable bowls, you can melt the cheese on the bread separately.
Brown the onions slowly. Melt the butter with the oil in a heavy 4-quart saucepan or Dutch oven over medium-low heat. Add the onions and stir to coat. Cook for 25 to 30 minutes, stirring every few minutes, until they are very soft and deeply golden. Lower the heat if the edges are getting dark before the middle of the pan has softened. The goal is sweet, browned onions, not crisp or burnt ones; this step supplies much of the soup’s homemade flavor.
Deglaze the pan. If using sherry, pour it over the onions and stir for about 30 seconds, scraping up the browned bits on the bottom of the pot. Let the liquid mostly evaporate. Those browned bits add savoriness, but if they look black or smell burnt, do not scrape them into the soup. Skip the sherry without replacing it if you prefer a nonalcoholic version; the soup will still be flavorful.
Simmer the soup. Stir in the canned soup, beef broth, water, Worcestershire sauce, thyme, bay leaf, and black pepper. Bring the mixture just to a gentle simmer, stirring so the condensed soup blends evenly with the liquids. Cook uncovered for 8 to 10 minutes, stirring occasionally. Avoid a hard boil, which can reduce the liquid too quickly and make the soup taste overly concentrated. Remove and discard the bay leaf, then taste before adding salt. Canned soup and broth can both be salty, so add salt only if the finished broth needs it.
Toast the bread. While the soup simmers, heat the oven to 400°F (200°C). Arrange the baguette slices in one layer on a baking sheet and toast for 5 to 7 minutes, turning once if needed, until dry and lightly golden. Toasting helps the bread hold its shape in the soup. Keep an eye on thin slices, which can brown faster than thick ones. If your oven is occupied or you do not want to heat it, toast the slices in a skillet over medium heat instead.
Assemble the bowls. Ladle the hot soup into four broiler-safe bowls, leaving a little room at the top. Set one or two toast slices on each bowl, depending on their size, then cover the bread generously with Gruyère. Put the bowls on a sturdy baking sheet before moving them; the sheet makes handling hot, full bowls safer and catches drips. For the separate-toast option, spoon cheese onto the bread and broil it on a baking sheet instead.
Melt the cheese and serve. Broil the bowls on the upper-middle oven rack for 2 to 4 minutes, watching continuously, until the cheese is melted, bubbling, and spotted golden. Broilers vary, so do not walk away: cheese can go from browned to scorched quickly. Use oven mitts to remove the baking sheet, and let the bowls stand for 2 minutes before serving because the soup and ceramic will be extremely hot. If broiling cheese separately, float each cheesy toast on the soup just before serving.

Tips

Take time with the onions. The canned base makes this recipe convenient, but well-browned onions keep it from tasting like soup simply poured from a can. Cook over moderate or low heat and stir regularly. If the pan becomes dry or the onions begin sticking, add a tablespoon of water and scrape the bottom; avoid turning up the heat to rush them.
Adjust liquid to the can you have. This recipe assumes condensed soup. If your can is labeled ready-to-serve rather than condensed, begin with the soup and omit the cup of water; add broth gradually until the soup tastes balanced. Different brands and varieties vary in salt and strength, so tasting before seasoning is more reliable than adding salt by habit.
Choose a good melting cheese. Gruyère gives a nutty, rich topping and is traditional in many gratinée-style versions. If it is hard to find, use Swiss cheese or Emmental for a similar melt, though the flavor will be milder. A little Parmesan mixed with mozzarella works in a pinch, but mozzarella alone is less savory and can become stretchy rather than forming a browned, flavorful top.
Keep bread and soup separate until serving. Bread left in the pot absorbs liquid and becomes soft. Toasting it well and assembling individual bowls just before broiling gives you a sturdier center and a crisp edge. If the onions or soup taste too concentrated, stir in water or broth a few tablespoons at a time rather than trying to correct the whole pot at once.

Serving Suggestions

Serve the soup immediately while the cheese is bubbling, with each person getting a little bread and browned cheese in every spoonful. Since it is rich and filling, a crisp green salad with a simple vinaigrette is an easy side. The acidity and crunch make a pleasant contrast without competing with the savory broth. A plate of roasted vegetables or steamed green beans also works if you want a more substantial meal.

For a casual dinner, bring the saucepan and a basket of extra toasted baguette slices to the table, then let people add bread as they eat. That approach is useful if some diners prefer less bread or want the toast on the side. Serve any extra shredded cheese separately, rather than adding it to the pot, so it does not clump or make the remaining soup difficult to store.

Variations

Make it without beef broth: Use vegetable broth instead. It gives the soup a lighter, less meaty flavor, so taste carefully and consider adding another teaspoon of Worcestershire sauce if it suits your diet; many Worcestershire sauces contain anchovies. For a vegetarian version, choose vegetarian Worcestershire or omit it, and check that both the canned soup and cheese fit your needs. Some canned French onion soups contain beef stock even when the label wording is not obvious.

Use another cheese: Swiss or Emmental are close, dependable alternatives to Gruyère. Provolone melts smoothly but is milder, while a small amount of Parmesan adds a salty, nutty note. Keep the total amount near 1 1/2 cups (150 g), and avoid piling cheese too thickly; a thinner, even layer melts before the bread underneath dries out.

Add mushrooms: Brown 8 ounces (225 g) sliced cremini mushrooms in the pan after the onions are cooked, then continue with the recipe. The mushrooms add an earthy flavor and make the soup heartier. Cook off their released moisture before adding the canned soup and broth so the finished broth does not become watery.

Make individual portions without broiler-safe bowls: Spoon the soup into regular heatproof bowls and serve with cheese-topped toast melted on a baking sheet. This keeps the gratin-style topping while avoiding direct broiler heat on bowls that may not be designed for it. You can also skip the broiler and place a slice of toast with cheese in each bowl, allowing the hot soup to soften the cheese; the top will not brown, but the flavor will still be satisfying.

Storage and Reheating

For the best texture, store the soup without the bread and cheese. Transfer leftovers to a shallow covered container and refrigerate within 2 hours of cooking; they keep for 3 to 4 days. Keep toasted bread in a separate airtight container at room temperature for a day, or toast fresh slices when serving again. The bread loses its crispness if refrigerated on top of the soup, and a fully assembled bowl is not ideal for storing.

Reheat the soup gently in a saucepan over medium-low heat, stirring occasionally, until steaming throughout. Add a splash of water or broth if it has thickened in the refrigerator. Reheat leftovers to 165°F (74°C), checking the center with a food thermometer; USDA FSIS recommends this temperature for reheated leftovers. Toast fresh bread, add cheese, and broil just before serving. You can freeze the soup base without bread or cheese for up to 2 to 3 months for best quality. Thaw it in the refrigerator overnight and reheat thoroughly; the onions may soften further, but the flavor remains suitable for a quick meal.

Frequently Asked Questions

Can I use canned French onion soup without adding broth?
Yes, but the recipe assumes condensed soup and uses broth plus water to make a generous, balanced pot. If you prefer a stronger flavor, reduce the broth or water gradually. If the can is ready-to-serve rather than condensed, do not automatically add the full amount of liquid; taste and adjust as you heat it.

How do I keep the soup from tasting too salty?
Use low-sodium broth, do not add salt before tasting, and add water a little at a time if the soup is too intense. The canned soup is already seasoned, and cheese adds more salt. A small amount of extra browned onion or unsalted broth can also soften a strong salty impression without masking the onion flavor.

Can I make the soup ahead?
Yes. Cook the soup base up to 3 days ahead and refrigerate it promptly. Reheat it thoroughly, toast the bread, then add the cheese and broil the bowls right before serving. Preparing the toppings separately keeps the bread crisp and gives the cheese its best melted texture.

What bread works if I do not have a baguette?
Use a sturdy country loaf, sourdough, or another crusty bread cut into slices about 1/2 inch (1.3 cm) thick. Very soft sandwich bread tends to collapse quickly, especially if it is not toasted first. If your slices are small, use two per bowl so the topping covers enough of the soup.

Can I make this recipe vegetarian?
Yes, but check the labels: canned French onion soup and Worcestershire sauce may contain beef stock or anchovies. Choose a vegetarian canned soup and vegetable broth, then use vegetarian Worcestershire or leave it out. Gruyère is traditionally made with animal rennet in some versions, so choose a cheese made with vegetarian rennet if that matters to you.

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