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The wonderful thing about making a big pot of soup is that it’s so easy to portion out leftovers for future meals.

But how should you reheat those leftovers?

I take a look at three different ways to reheat French onion soup, as well as tips on how to store your leftovers.

In a rush? Here’s the short answer:

The best way to reheat French onion soup is on the stove. Pour the soup into a cold pan and heat over a medium heat, stirring frequently. Next, toast some bread and grate some cheese. Portion the reheated French onion soup into heatproof bowls, add the toppings, and broil until the cheese melts.

A note on my experiment

When it came to reheating French onion soup, I was looking for the best results in terms of taste and ease of preparation.

I tested three different methods for reheating leftover French onion soup:

On the stove (best method, most like the first day)
In the oven (tasted fine but more time-consuming)
In the microwave (quick but only works for single portions)

With all these methods, you have to separately prepare your cheesy croutons or toasted bread if you’re using them.

You can use pre-made ones or make them fresh.

If you decide against a traditional finish, you can just add some regular croutons and grated cheese to the bowls of reheated soup.

Related: Can You Freeze Croutons

Reheating French onion soup on the stove

Pour the French onion soup into a cold pot and heat over a medium heat, stirring frequently. While the soup is heating, toast some bread and grate some cheese. Ladle the hot soup into heatproof bowls and top each serving with the bread and cheese. Briefly broil to melt the cheese.

You can also use pre-made cheesy croutons if you have them.

If you don’t have an oven or broiler to melt the cheese in, you can use the microwave or even place the cheesy bread in a skillet and cover it with a lid.

After a few minutes of heating, the cheese will have melted.

How to reheat French onion soup on the stove:

Pour your leftover French onion soup into a cold pot.
Heat over a medium heat, stirring frequently.
Toast some bread and grate some cheese.
Ladle hot soup into heatproof bowls.
Top with the bread, then cheese.
Broil until the cheese is melted (or pre-melt the cheese on the bread in the microwave).

While heating the soup, be sure to keep stirring frequently. This will keep the onions in the soup from sticking to the bottom of the pot and burning.

If the soup has thickened in the fridge, add additional broth or water as needed.

My verdict

This was my favorite method out of the three I tried.

You can heat as much or as little as you want to need. Plus, it’s easy to control the temperature of the soup.

You can also taste the soup as you heat it and add additional flavors or seasoning if desired.

Reheating French onion soup in the oven

Preheat the oven to 350ºF (180ºC). Pour the soup into an oven-safe dish and cover with foil. Heat the soup for 10-20 minutes. While heating, prepare some toast and grated cheese. Ladle the hot soup into bowls, add the bread and cheese, and broil until the cheese is melted.

The timings are approximate – it will depend a lot on how much soup you have and what kind of oven you’re using.

Check the soup regularly to avoid overheating.

How to reheat French onion soup in the oven:

Preheat the oven to 350ºF (180ºC).
Pour your French onion soup into a large oven-safe dish and cover tightly with foil. Add some extra liquid (stock or water) if the soup seems thick.
Heat for 10-20 minutes until heated through, stirring occasionally.
Toast some bread and grate some cheese while the soup is heating in the oven (or retrieve your pre-made cheesy croutons).
Ladle hot soup into individual bowls and top with the toasted bread and cheese.
Broil or heat in the oven until the cheese is melted.

If you want, you can toast the bread in the oven at the same time as the soup is reheating.

You may have to flip the bread halfway through to ensure even toasting.

The foil over the oven-safe dish during the initial reheating process prevents too much evaporation of the broth.

My verdict

In terms of the final product, this method had a similar result as the stovetop method.

But reheating in the oven takes much longer overall (especially if you’re only heating one or two portions).

Reheating French onion soup in the microwave

Pour soup into a microwave-safe container or bowl and cover. Heat on HIGH in 30-second intervals, pausing after each interval to stir and check the heat. When the soup is nearly hot enough, top with some toasted bread and cheese and microwave for a final 20 seconds to melt the cheese.

You can also melt the cheese under the broiler if you prefer.

How to reheat French onion soup in the microwave:

Pour the French onion soup into a microwave-safe dish and cover with something to prevent splatters.
Heat on HIGH in 30-second intervals, stirring after each interval.
When the soup is hot, top it with some toasted bread and add grated cheese (or pre-made cheese croutons).
Heat the soup for 20 seconds more or until the cheese is melted.

Melting the cheese in the microwave will be very quick and leave it super gooey.

But if you want a browned top, you’ll have to use the broiler instead.

To cover the soup you can use plastic wrap, a paper towel or a lid thats slightly ajar.

My verdict

As is often the case with reheating in the microwave, this method was the quickest and worked fine.

But the microwave is really only good for one or two servings. If you have a lot of soup to reheat, it’s not worthwhile.

If you already have the toasted bread or cheesy croutons ready to go, this method is especially fast as you aren’t wasting extra prep time.

How to store French onion soup

You can store french onion soup in airtight containers in the fridge for 3-4 days. If there is any leftover bread already in the soup, discard it. It will either turn into a soggy mess or disintegrate into the soup liquid. Plan to make new cheesy bread when you reheat the soup.

If you have leftover cheesy bread that has not already been put in the soup, cool it to room temperature and wrap it up separately in aluminum foil to reheat later.

You can keep the cheesy bread in the fridge, but it will get very stale after a day or two.

Keep the broth and bread apart.

Can you freeze French onion soup?

As long as there is no bread included, French onion soup will freeze very well. Make sure it has cooled to room temperature before freezing. The soup will keep in the freezer for up to three months.

You can freeze leftover cheesy bread separately if desired or make it fresh when you reheat the soup.

How to freeze French onion soup:

Cool soup to room temperature. This will help the soup freeze quickly and preserve the texture of the onions.
Pour cooled soup (broth and onions only) into freezer bags.
Remove excess air and seal tightly.
Lay the bags flat on the freezer shelf and freeze.
Wrap leftover cheesy bread tightly in plastic wrap and aluminum foil, then place in a freezer bag.

You can also keep the soup in airtight containers. Just make sure there is enough soup to fill the container.

I prefer using freezer bags because they stack really well in the freezer and save a lot of space.

How to reheat frozen French onion soup

To reheat frozen French onion soup, you can either thaw the soup in the refrigerator overnight or reheat it directly from the freezer.

I recommend the stovetop or microwave for reheating frozen soup. Reheat the soup slowly (low heat or 50% power) and break up the chunks of frozen soup as soon as possible to ensure even heating. Once the soup has melted, you can use more heat.