I finally nailed the Best French Onion Soup and I’ll share versions for the Slow Cooker, Stove Top, and Instant Pot so you can choose the method that fits your day.

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I can’t resist a pot of French onion soup, and this version made in the Slow Cooker, Stove Top, or Instant Pot always pulls people in. Slowly caramelized yellow onions give the broth that deep, almost sweet edge, and melted Gruyere cheese on top makes it impossible not to taste.

I tried an Instapot French Onion Soup once and it actually stunned me, friends even called it the Best French Onion Soup they’ve had. I keep tweaking little things, sometimes I mess up, but the result is almost always worth it, you’ll want to try it.

Ingredients

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Yellow onions: high in fiber and flavor, they sweeten when cooked and add depth.
Butter and olive oil: add richness and fat, help caramelize, not exactly healthy in excess.
Granulated sugar: a little speeds browning and boosts sweetness, use sparingly tho.
Dry white wine: brings acidity and brightness, deglazes pan and lifts flavors.
Low sodium beef broth: provides savory depth and some protein, helps control overall salt.
Baguette: crunchy carb topping, soaks up the soup and balances salty richness.
Gruyere cheese: melty nutty adds protein and a gooey golden gratin finish.

Ingredient Quantities

5 large yellow onions, thinly sliced (about 3 lb)

3 tablespoons unsalted butter

1 tablespoon olive oil

1 teaspoon granulated sugar

1 tablespoon all purpose flour

1 cup dry white wine (optional)

2 tablespoons brandy or cognac (optional)

6 cups low sodium beef broth

1 tablespoon Worcestershire sauce

1 bay leaf

2 sprigs fresh thyme or 1 teaspoon dried thyme

1 1/2 teaspoons kosher salt

1/2 teaspoon freshly ground black pepper

1 baguette, sliced

8 ounces Gruyere cheese, grated

2 ounces Parmesan cheese, grated (optional)

How to Make this

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1. Prep everything: thinly slice 5 large yellow onions, grate 8 oz Gruyere and 2 oz Parmesan, slice the baguette, measure butter, olive oil, sugar, flour, wine and brandy if using, beef broth, Worcestershire, bay leaf, thyme, salt and pepper. Do this first, it saves time and you wont panic later.

2. Caramelize the onions on the stove: melt 3 tablespoons butter with 1 tablespoon olive oil in a large heavy pot over medium heat, add the onions and 1 teaspoon sugar and a good pinch of the 1 1/2 teaspoons kosher salt, cook stirring every few minutes until deep golden brown and sweet, about 40 minutes. Be patient, this is the flavor base.

3. If you want to skip some time, you can caramelize in the Instant Pot using the Sauté function for 20 to 30 minutes, stirring often, or caramelize briefly on the stove and transfer to the slow cooker; in the slow cooker cook on low for 6 to 8 hours to get color and sweetness.

4. When onions are well browned, sprinkle 1 tablespoon flour over them and cook 1 to 2 minutes to remove raw flour taste. Add 1 cup dry white wine to deglaze the pot scraping up browned bits, then stir in 2 tablespoons brandy or cognac if using and let the alcohol cook off for a minute.

5. Add 6 cups low sodium beef broth, 1 tablespoon Worcestershire sauce, 1 bay leaf and 2 sprigs fresh thyme or 1 teaspoon dried thyme, plus 1/2 teaspoon freshly ground black pepper. For stovetop simmer 20 to 30 minutes with lid slightly ajar. For Instant Pot after deglazing add broth and set to Manual high pressure for 5 minutes then quick release. For slow cooker combine everything and cook on low 4 to 6 hours if you didn’t caramelize long on the stove.

6. While the soup simmers toast the baguette slices: place on a baking sheet, brush lightly with butter or olive oil, and toast in a 375 degree oven until crisp and just golden, about 8 minutes. Don’t skip this step, soggy bread is sad.

7. Turn oven to broil. Ladle soup into ovenproof bowls, float a toasted baguette slice or two on top of each bowl, pile grated Gruyere over the bread and sprinkle the Parmesan on top if using.

8. Broil the bowls until the cheese is bubbly and browned, about 2 to 4 minutes. Watch closely, it goes from perfect to burnt fast. If you prefer, bake at 425 degrees for 8 to 10 minutes instead.

9. Remove bay leaf and thyme sprigs before serving, garnish with a little extra thyme if you want and let the bowls rest 3 to 5 minutes so the soup isnt scalding hot.

10. Serve immediately, warn everyone the bowls will be hot, and expect lots of compliments because this is the kind of comfort food that actually tastes like effort.

Equipment Needed

1. Large heavy pot or Dutch oven (for caramelizing and simmering)
2. Chef’s knife (for thinly slicing the onions)
3. Cutting board
4. Box grater (for Gruyere and Parmesan)
5. Wooden spoon or heatproof spatula, for stirring (dont use metal if pot is nonstick)
6. Measuring cups and spoons
7. Baking sheet (to toast the baguette)
8. Ovenproof bowls or crocks plus a ladle and oven mitts, for broiling and serving

FAQ

How long does it take to caramelize the onions? Answer: Plan on 45 to 60 minutes over medium-low heat, stirring every 5 to 10 minutes. Take your time, patience makes the onions sweet and deeply brown. If they scorch lower the heat and stir more often.

Can I skip the wine and brandy? Answer: Yes, both are optional. Wine and brandy add depth and complexity but you can omit them and just use extra broth, or add a splash of balsamic vinegar for some acidity if you want.

Can I make this vegetarian or vegan? Answer: You can, but use a rich vegetable or mushroom broth instead of beef, swap Worcestershire for a vegan version or a splash of soy sauce, and use vegan cheese or skip the cheese. Dont add bread before freezing.

Why is there flour in the recipe and is it necessary? Answer: The tablespoon of flour lightly thickens the broth and helps coat the onions so the soup feels silky. It's optional though, the soup will still be great without it, just a bit thinner.

How should I store and reheat leftovers? Answer: Cool then refrigerate in a sealed container for 3 to 4 days. For longer storage freeze only the soup (no bread or cheese) for up to 2 to 3 months. Reheat gently on the stove, then assemble bread and cheese only when you're ready to broil and serve.

Any tips for keeping the bread from getting soggy? Answer: Slice and toast the baguette first, even rubbing with a little garlic if you like. Put the toasted bread on top of the soup right before you add the cheese and broil so it stays crunchy beneath the melted cheese.

French Onion Soup Recipe Substitutions and Variations

Onions: use sweet onions (Vidalia or Walla Walla) instead of yellow, or white onions for a brighter bite, or swap in 3-4 shallots for a sweeter, more delicate flavor, or add sliced leeks for extra depth
Butter + olive oil: use all butter for a richer soup, or just olive oil if you want less dairy, or use ghee for a nutty note, or vegan butter / neutral oil (canola) if dairy free
Beef broth: replace with low sodium chicken broth in a pinch, or a mushroom or soy-enhanced vegetable broth for extra umami (good for vegetarians), or dissolve beef bouillon/consommé for a stronger beefy taste
Gruyere cheese: swap with Emmental or Comte for similar melt and flavor, or use fontina or young provolone, or a sharp white cheddar if you like bolder flavor; sprinkle a little Parmesan for extra saltiness

Pro Tips

– Be patient with the onions, dont rush the color. Low and slow gives that deep sweet flavor everyone thinks you worked on for hours. If edges start to scorch, turn the heat down and add a splash of broth or water to loosen the fond, scrape the pot, then carry on.

– Make the flour foolproof by whisking it into a few tablespoons of cold broth first so you dont get lumps. Add it after the onions are well browned and let it cook a minute so the raw flour taste is gone before you add the rest of the liquid.

– Toast the baguette until it’s way more than just golden, make it almost dry, that way it wont go soggy under the cheese. If you broil the bowls, move the rack lower or use the 425 degree bake option if the cheese is browning too fast; broilers burn in a blink so watch it.

– Do as much ahead as you can. Caramelized onions store beautifully in the fridge or freezer and the soup actually tastes better the next day. When reheating, warm gently and add a bit of broth if it seems thick, and always adjust salt at the end since cheese and broth can change the seasoning.

French Onion Soup Recipe

Recipe by Jot Punji

0.0 from 0 votes

I finally nailed the Best French Onion Soup and I’ll share versions for the Slow Cooker, Stove Top, and Instant Pot so you can choose the method that fits your day.

Servings

servings

Calories

526

kcal

Equipment: 1. Large heavy pot or Dutch oven (for caramelizing and simmering)
2. Chef’s knife (for thinly slicing the onions)
3. Cutting board
4. Box grater (for Gruyere and Parmesan)
5. Wooden spoon or heatproof spatula, for stirring (dont use metal if pot is nonstick)
6. Measuring cups and spoons
7. Baking sheet (to toast the baguette)
8. Ovenproof bowls or crocks plus a ladle and oven mitts, for broiling and serving

Ingredients

5 large yellow onions, thinly sliced (about 3 lb)
3 tablespoons unsalted butter
1 tablespoon olive oil
1 teaspoon granulated sugar
1 tablespoon all purpose flour
1 cup dry white wine (optional)
2 tablespoons brandy or cognac (optional)
6 cups low sodium beef broth
1 tablespoon Worcestershire sauce
1 bay leaf
2 sprigs fresh thyme or 1 teaspoon dried thyme
1 1/2 teaspoons kosher salt
1/2 teaspoon freshly ground black pepper
1 baguette, sliced
8 ounces Gruyere cheese, grated
2 ounces Parmesan cheese, grated (optional)

Directions

Prep everything: thinly slice 5 large yellow onions, grate 8 oz Gruyere and 2 oz Parmesan, slice the baguette, measure butter, olive oil, sugar, flour, wine and brandy if using, beef broth, Worcestershire, bay leaf, thyme, salt and pepper. Do this first, it saves time and you wont panic later.
Caramelize the onions on the stove: melt 3 tablespoons butter with 1 tablespoon olive oil in a large heavy pot over medium heat, add the onions and 1 teaspoon sugar and a good pinch of the 1 1/2 teaspoons kosher salt, cook stirring every few minutes until deep golden brown and sweet, about 40 minutes. Be patient, this is the flavor base.
If you want to skip some time, you can caramelize in the Instant Pot using the Sauté function for 20 to 30 minutes, stirring often, or caramelize briefly on the stove and transfer to the slow cooker; in the slow cooker cook on low for 6 to 8 hours to get color and sweetness.
When onions are well browned, sprinkle 1 tablespoon flour over them and cook 1 to 2 minutes to remove raw flour taste. Add 1 cup dry white wine to deglaze the pot scraping up browned bits, then stir in 2 tablespoons brandy or cognac if using and let the alcohol cook off for a minute.
Add 6 cups low sodium beef broth, 1 tablespoon Worcestershire sauce, 1 bay leaf and 2 sprigs fresh thyme or 1 teaspoon dried thyme, plus 1/2 teaspoon freshly ground black pepper. For stovetop simmer 20 to 30 minutes with lid slightly ajar. For Instant Pot after deglazing add broth and set to Manual high pressure for 5 minutes then quick release. For slow cooker combine everything and cook on low 4 to 6 hours if you didn’t caramelize long on the stove.
While the soup simmers toast the baguette slices: place on a baking sheet, brush lightly with butter or olive oil, and toast in a 375 degree oven until crisp and just golden, about 8 minutes. Don’t skip this step, soggy bread is sad.
Turn oven to broil. Ladle soup into ovenproof bowls, float a toasted baguette slice or two on top of each bowl, pile grated Gruyere over the bread and sprinkle the Parmesan on top if using.
Broil the bowls until the cheese is bubbly and browned, about 2 to 4 minutes. Watch closely, it goes from perfect to burnt fast. If you prefer, bake at 425 degrees for 8 to 10 minutes instead.
Remove bay leaf and thyme sprigs before serving, garnish with a little extra thyme if you want and let the bowls rest 3 to 5 minutes so the soup isnt scalding hot.
Serve immediately, warn everyone the bowls will be hot, and expect lots of compliments because this is the kind of comfort food that actually tastes like effort.

Notes

Below you’ll find my best estimate of this recipe’s nutrition facts. Treat the numbers as a guide rather than a rule—great food should nourish both body and spirit. Figures are approximate, and the website owner assumes no liability for any inaccuracies in this recipe.