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Home » Recipes » Soup

Sweet French Onion Soup

felice kaufman author bio
Modified: Mar 29, 2026 · by Felice Kaufman · This post may contain affiliate links · 1 Comment
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Sweet French Onion Soup has become a favorite in my kitchen. It's sweet, just like the sweet bistro-style soup you get in a restaurant. I mix bone broth, onions, sherry, and a spoon of Better Than Bouillon into my bone broth. This gives the soup an incredible, rich flavor.

French onion soup in a white crock topped with toasted bread, melted cheese, cracked pepper, and fresh thyme.

Homemade Onion Soup

I make a lot of bone broth. I sip it through the day and enjoy it, but my husband won't go near it. Since he loves French onion soup, I mixed my bone broth with onions and some spices. I created this recipe to taste better than what he had in restaurants.

I started testing onion soup recipes. One batch wasn't sweet enough. Another fell flat. Nothing tasted the way I imagined, but at least he was getting the bone broth.

Then I remembered a chef I worked for years ago who always added a spoon of Better Than Bouillon (Amazon link) to his soups. I tried it in mine and the flavor got the lift I was looking for.

For the wine, I use Harvey's Bristol Cream. It's a sweet sherry from the UK, usually served after dinner, but it adds the perfect taste to this soup.

onion soup ingredients

Ingredients

  • Yellow onions
  • Unsalted butter
  • Kosher salt and pepper
  • Sugar
  • Beef bone broth, beef broth, or bottled water 
  • Better Than Bouillon, beef flavor (the organic version doesn't taste as good)
  • Harvey's Bristol Cream sherry
  • Swiss cheese or Gruyere (French Swiss cheese)
  • French bread

The Soup

The secret to my onion soup is the bone broth. It gives the soup a deep flavor and silky mouthfeel you can't get from boxed stock or water.

Making the broth takes some effort. It cooks for three to 12 hours, then chills so you can skim off the fat. Once that's done, you're ready to make the soup.

If you don't have homemade broth, you can use filtered water.

Here's my bone broth recipe if you want the best onion soup ever!

slicing onions

The Onions

I use yellow onions. You can use vidalia, yellow, red, or white onions. You can mix several varieties together.

The Crouton

Toasted bread makes a crouton that holds up the cheese so it drips right down the sides of the crock.

Start with a thinly sliced baguette or a bakery sliced bread such as sourdough. Toast the bread in the oven for a few minutes to firm it up.

Two brown onion-soup crocks filled with toasted baguette slices, topped with thinly sliced Swiss cheese draped over the rims, ready to go under the broiler.

The Cheese

Don't you love picking off the crusty cheese that melts down the sides of the bowl? It's the best part.

You can use freshly shredded cheese, but try to skip pre-grated cheese if you can. The anti-caking powders keep it from melting correctly.

Gruyère, traditionally used in French onion soup is a Swiss cheese, has a richer flavor and melts really well. However, I've made this soup with expensive Gruyère, and it didn't make a big difference. The real flavor comes from the broth.

I use packaged thinly sliced Swiss cheese. By using sliced cheese, i get the perfect drip over the edge of the bowl.

Place a few toasted croutons inside the bowl and another two resting on top. Lay the cheese slices over the bread and let them hang over the sides. As the soup bakes, the cheese melts and drips down the bowl.

Broiling vs. Baking the Cheese

To get that brown crust on top, the soup needs the broiler. But you can only broil it if your soup crocks are broiler-safe. I don't own any, but if I did, I'd place the crocks on a foil-lined sheet pan and broil them for about 2 minutes.

Since my soup bowls can't go under the broiler, I bake the soup at 400°F. I bake it for 10 to 15 minutes until the cheese is melted and bubbly.

Ingredient Notes

  • Onions: Use plenty of onions, yellow, white, red, or a mixture.
  • Beef Broth: Homemade beef bone broth gives the soup its rich flavor. If you don't have time to make it, use water.
  • Umami flavor: Better Than Bouillon (beef flavor) is a concentrated paste made from roasted beef and seasonings. I buy this one on Amazon.
  • Sherry: Harveys Bristol Cream Sherry is the only
  • Crouton: Use French bread or baguette slices.
  • Cheese: Swiss cheese , Gruyere, or freshly grated mozzarella.

How to Make French Onion Soup

  • Melt 2 tablespoons of butter in a heavy-bottomed skillet over medium heat.
  • Add the onions and stir. 
  • Cook, stirring occasionally, for 15 minutes. Add a big pinch of salt and a tablespoon of sugar and cook another 15-25 minutes until golden brown.
cooking onions for onion soup
  • Heat the bone broth or water in a large pot over medium-high heat.
  • Add the Better Than Bouillon and whisk until dissolved. Lower the heat to medium, cover, and keep warm while the onions finish cooking.
  • Transfer the caramelized onions to the soup pot with the broth.
onion soup with sherry
  • Raise the heat of the now-empty skillet to medium-high.
  • Add a cup of sherry and boil, scraping up the browned bits from the bottom of the pan with a wire whisk.
  • Let the sherry reduce until thick and syrupy enough to coat the back of a spoon.
  • Pour the sherry mixture into the soup pot, scraping out as much as possible with a rubber spatula.
  • Raise the heat of the soup pot to medium-high and bring the soup to a boil.
  • Lower the heat to a simmer (just below boiling) with the pot partially covered.
  • Cook 20 minutes.

For the Croutons

While the soup is cooking, preheat the oven to 400°F.

Scatter the bread slices on a pizza screen or parchment lined sheet pan. Toast 4-5 minutes.

Assemble the Soup

You may get different yields based on the size of your crocks. Fill each one about three-quarters full. Then, add the bread and cheese.

  • Line a baking sheet with parchment paper or foil.
  • Place 4-6 oven-safe soup crocks on the baking sheet.
  • Ladle soup into the crocks, filling each about ¾ full (depending on the size of you crocks)
  • Lay a few slices of toasted bread over each crock and cover the toast with cheese.
sweet onion soup

Serving

  • Carefully remove the crocks from the oven and place each on a dinner plate.
  • If your crocks have handles, tie a cloth napkin around each handle for easier handling.
  • Serve hot.

Top Tips for French Onion Soup

Freeze for Later: Store leftover soup (without bread and cheese) in freezer-safe containers for easy reheating and serving. Add fresh croutons and cheese when ready to bake.

Caramelize Slowly: Cook the onions over medium-low heat, stirring often.

Homemade Broth: Make bone broth for a deeper, more complex flavor. 

Use Oven-Safe Crocks: Make sure your bowls can handle the oven heat for the cheese topping to melt perfectly.

Toast the Bread First: Lightly toasting the bread keeps it from getting too soggy when topped with cheese and baked.

Get the Right Cheese: Swiss or Gruyere cheese melts and pulls and gives the soup its iconic, gooey topping.

Storage and Reheating

  • Let the soup cool all the way down, then move it to an airtight container. It keeps in the fridge for about four days. Warm it in a saucepan before adding the bread and cheese.
  • For longer storage, freeze the soup on its own in freezer-safe containers for up to three months.
  • It freezes well. I thaw it, heat it on the stove, toast fresh bread, add the cheese, and bake or broil it until it's bubbling.

Sides For Onion Soup

Onion soup can be a starter or a full meal. Serve it with a simple green salad with roasted chicken, steak, or a sliced turkey or chicken sandwich.

Here are a few recipes that would be great with your onion soup.

  • Seared NY Strip Steak
  • Standing Rib Roast
  • Roasted Chicken
  • Mixed Roasted Vegetables
  • Pan-Seared Fish Fillets
  • Tuna Salad
  • Sonoma Chicken Salad Sandwich
Close-up of homemade onion soup with a golden cheese crust and herbs sprinkled on top.

The Best French Onion Soup

French onion soup is a classic. Sweet caramelized onions, rich broth, and cheese bubbling over toasted bread make it hard to beat.

Making the bone broth takes time, but it's worth it. I usually get a few meals out of it.

After a few tries, I found that Harvey's Bristol Cream and a spoonful of Better Than Bouillon add a rich, restaurant-style flavor.

FAQ

What is Harvey's Bristol Cream?

Harvey's Bristol Cream is a sweet sherry from Spain made from a blend of several types of sherry. It has a rich, nutty flavor with hints of caramel and dried fruit. 

Can French onion soup be frozen?

Yes. Let the soup cool completely, then freeze it without the bread or cheese topping. When ready to serve, thaw, heat on the stove, and add fresh croutons and cheese before baking.

Can French onion soup be made with red onions?

Yes. Red onions add a deeper color and a slightly stronger flavor. Many cooks mix red, yellow, and white onions.

How did French onion soup originate?

French onion soup dates back to 18th-century France. It was a peasant dish made from simple ingredients: onions, bread, and broth. Over time, it became a classic in French restaurants.

How do you eat French onion soup?

Use your spoon to break through the cheese layer and scoop up a bit of soup, bread, and cheese in each bite. It's served piping hot, so let it cool a minute before taking a bite.

Bowl of French onion soup with a thick slice of bread baked under melted Gruyère, served on a plate with a spoon.

French Onion Soup

Felice Kaufman
Sweet French Onion Soup made with slow-cooked onions, rich bone broth, and a splash of sherry. The cheese melts over toasted bread and bakes into a restaurant-style bowl of soup.
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Prep Time 30 minutes mins
Cook Time 40 minutes mins
Total Time 1 hour hr 10 minutes mins
Course Soup
Cuisine French
Servings 6
Calories 232.4 kcal

Ingredients
  

  • 1 pound (4 cups) thinly sliced yellow onions, (about 3-4 onions)
  • 3 tablespoons unsalted butter, divided
  • 1 teaspoon salt
  • 1 teaspoon sugar
  • 8 cups Homemade Beef Bone Broth or bottled water
  • 2 tablespoons Better Than Bouillon, beef flavor
  • 1 cup Harvey's Bristol Cream sherry (or other sweet sherry)
  • 1 thinly sliced baguette, ½-inch slices
  • 6 slices of Swiss or grated Gruyere cheese

Instructions
 

For The Soup

  • Melt 2 tablespoons of butter in a heavy-bottomed skillet over medium heat. Add the onions and stir.
  • Cook, stirring occasionally, for 15 minutes. Add a big pinch of salt and a tablespoon of sugar and cook another 30 minutes until golden brown.
  • While the onions cook, heat the bone broth or water in a large pot over medium-high heat.
  • Add the Better Than Bouillon and whisk until dissolved. Lower the heat to medium, cover, and keep warm while the onions finish cooking.
  • Transfer the caramelized onions to the soup pot with the broth.
  • Raise the heat of the now-empty skillet to medium-high.
  • Add a cup of sherry and boil, scraping up the browned bits from the bottom of the pan with a wire whisk.
  • Let the sherry reduce until thick and syrupy enough to coat the back of a spoon. Stir in a tablespoon of butter.
  • Pour the sherry mixture into the soup pot, scraping out as much as possible with a rubber spatula.
  • Raise the heat of the soup pot to medium-high and bring the soup to a boil.
  • Lower the heat to a simmer (just below boiling) with the pot partially covered. Cook 20 minutes.

For the Croutons

  • Preheat the oven to 400°F.
  • Scatter the bread slices on a pizza screen or parchment lined sheet pan. Toast the slices of bread for 4-5 minutes.

Assemble the Soup

  • Line a baking sheet with parchment paper or foil.
  • Place 4-6 oven-safe soup crocks on the baking sheet. Ladle soup into the crocks, filling each about ¾ full.
  • Lay a few slices of toasted bread over each crock and cover the toast with 3 slices of Swiss or Gruyere cheese.
  • Place the pan in the oven until the cheese is melted and bubbly, about 15 minutes. Serve hot.

Notes

Storage and Reheating
  • Let the onion soup cool completely, then transfer it to an airtight container. It keeps in the fridge for up to 4 days.
  • For longer storage, freeze the soup without the bread and cheese in freezer-safe containers for up to 3 months.
  • The soup freezes great. I thaw it, warm it on the stovetop, toast fresh croutons, add the cheese, and bake it until bubbly.

Nutrition

Calories: 232.4kcalCarbohydrates: 19.1gProtein: 8.3gTotal Fat: 10.8gSaturated Fat: 6.3gCholesterol: 28.3mgSodium: 569.4mgPotassium: 179.8mgFiber: 1.7gSugar: 5.4gNet Carbohydrates: 17.4g
Tried this recipe? Leave a comment below & tag @cookinginthekeys on social!

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Comments

  1. Mr J says

    November 21, 2025 at 10:02 am

    5 stars
    My favorite! Better than any restaurant!

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Felice Kaufman image

Welcome!

Hi, I’m Felice. I live in the Florida Keys and share easy recipes made with fresh seafood, steak, and seasonal vegetables. Everything is inspired by island life, simple, delicious, and made with real food.

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