Classic French Onion Soup
Three pounds of sweet onions go into one pot of this French onion soup, and they cook down to a dark, jammy layer you could spread on toast. That slow onion stage is where French onion soup gets its color and its depth.
I give the onions close to an hour over medium heat. It’s the one part I won’t hurry.
What I watch is the bottom of the pot. Once a brown film starts to stick there, I stir more often and scrape it back into the onions, since that film carries a lot of the flavor.
Everything after that moves fast. Wine, beef broth, a spoonful of sherry, crisp toast, and a thick cap of Gruyère that bubbles under the broiler.
Prep: 20 minutes · Cook: about 1 hour 40 minutes · Total: about 2 hours · Serves: 4 to 6
How long do you caramelize onions for French onion soup?
Plan on 45 to 55 minutes over medium heat, stirring now and then at first and more often as the onions darken. They’re done when they’re deep amber, very soft and jammy. If they brown faster than they soften, stir in a few spoonfuls of water and keep going.
Why This Recipe Works
- Medium heat for 45 to 55 minutes, the window Once Upon a Chef gives, browns the onions slowly enough that they soften all the way through before the color gets deep.
- Cooking 1 cup of dry white wine on high for 8 to 10 minutes, until it’s nearly gone, leaves its flavor in the onions without a raw wine taste in the broth.
- Two tablespoons of flour cooked with the onions for a minute give the broth a little body. Spend With Pennies leaves the flour out and simmers its soup uncovered for 1 hour, while this version goes covered for about 30 minutes.
I pull the onions when a spoon dragged across the pot leaves a clean path and the pile slumps back into it slowly. That’s my cue to pour in the wine.
Why This One’s Worth Making
- One heavy pot carries the whole soup, from the onions to the broth.
- The shopping list is short: onions, butter, wine, beef broth, a baguette, and two cheeses.
- The soup base freezes for up to 3 months, so the long onion stage can happen on a slow afternoon.
- The broiled cheese turns golden at the edges and stretches in long strands when the spoon goes in.
The Ingredient List
- 4 tbsp unsalted butter
- 1 tbsp vegetable oil
- 3 lb sweet onions, such as Vidalia (about 5), halved lengthwise and thinly sliced
- 3/4 tsp salt
- 1/2 tsp black pepper
- 3/4 tsp sugar
- 1 cup dry white wine
- 2 tbsp all-purpose flour
- 6 cups beef broth
- 1 tsp Worcestershire sauce
- 1/2 tsp dried thyme
- 2 bay leaves
- 1 tbsp dry sherry
- 1 small baguette, cut into 1/2-inch slices
- 8 oz Gruyère, grated (about 2 heaping cups)
- 1/2 cup grated Parmigiano Reggiano
Ingredient Notes
Sweet onions are what both classic sources call for, and Once Upon a Chef names Vidalia. Three pounds looks like far too much for one pot, but it shrinks down to a soft, dark layer.
Slice them as evenly as you can so thin pieces don’t race ahead of thick ones.
The wine should be dry. Onions this slow-cooked are already sweet, and a dry wine keeps the soup on the savory side.
The tablespoon of dry sherry goes in at the very end, and to me it sharpens the whole pot.
Gruyère is the main cheese here, with a half cup of Parmigiano Reggiano on top for a salty edge. I grate the Gruyère myself from a block so it melts into one smooth layer.
The baguette matters too. It has to be toasted dry all the way through, or it goes soft the moment it meets the hot broth.
Step-by-Step Directions
- Start the onions. Melt the butter with the oil in a large heavy pot over medium heat. Add the sliced onions, salt, pepper, and sugar, and toss until every slice is coated in fat and the pile starts to turn glossy and slump.
- Caramelize slowly. Cook over medium heat for 45 to 55 minutes, stirring now and then at first and more often as the color deepens. Scrape the brown film off the bottom each time. They’re ready when they’re deep amber, very soft, and jammy.
- Fix fast browning. If the bottom of the pot darkens before the onions have softened, stir in a few spoonfuls of water and scrape hard with a wooden spoon. The stuck film lifts back into the onions, and the pot looks glossy again.
- Reduce the wine. Pour in the wine, raise the heat to high, and cook for 8 to 10 minutes, stirring often. Stop when the liquid is nearly gone and the onions look thick and jammy, with no wine pooling around the edges.
- Cook the flour. Sprinkle the flour over the onions and stir for 1 minute. You’re done when no dry white streaks remain and the onions look lightly coated, a little pasty on the spoon.
- Simmer the soup. Add the beef broth, Worcestershire, thyme, and bay leaves and bring to a boil. Lower the heat, cover, and simmer for about 30 minutes, until the onions are silky. Fish out the bay leaves and stir in the sherry.
- Toast the bread. While the soup simmers, heat the oven to 400°F. Lay the baguette slices on a baking sheet and toast for about 10 minutes, until they’re dry and crisp all the way through and golden at the edges.
- Fill the bowls. Move an oven rack so the tops of the bowls will sit 6 inches from the broiler element, then switch the oven to broil. Set oven-safe bowls on a rimmed baking sheet, ladle in the hot French onion soup, and float 1 or 2 toasts on each.
- Broil the cheese. Pile the Gruyère and parmesan over the toast. Broil for 3 to 5 minutes, until the cheese is melted, bubbling, and golden at the edges. Let the bowls sit a few minutes before serving, because they’re extremely hot.
Tips for Success
- Don’t turn up the heat to rush the onions. Medium heat and close to an hour is where the soup’s depth comes from.
- I don’t weigh the Gruyère. Two heaping cups is close enough for me, and I’m not about to start measuring it now.
- Stay at the oven door while the cheese broils. It moves from melted to bubbling quickly, and 3 to 5 minutes passes fast.
- Keep the toast and cheese out of anything you plan to store. They’re added fresh right before broiling.
Make-Ahead and Leftovers
Leftover soup keeps in an airtight container in the fridge for up to 3 days. Store it without the toast and cheese, which turn soggy in the broth.
Spend With Pennies allows 4 days in the fridge, but I stick with 3. The soup base freezes well for up to 3 months, again with no bread or cheese.
Both classic sources agree on that 3-month window. Thaw it in the fridge before reheating.
Reheat the soup gently on the stove until it’s steaming. Then toast fresh baguette slices, fill the oven-safe bowls, and broil the cheese the same way you would for a fresh pot.
What to Serve With French Onion Soup
- A green salad with a sharp vinaigrette, since the acid cuts through all that melted cheese.
- Thin apple slices on the side, which give a crisp, cool bite between spoonfuls.
- Extra toasted baguette slices for dragging through the last of the broth.
Equipment Worth Having
- A large heavy pot or Dutch oven with a thick bottom, so the onions brown slowly and evenly instead of catching in hot spots.
- A flat-edged wooden spoon for scraping the brown film off the bottom of the pot.
- Oven-safe soup bowls or crocks that can handle the broiler.
- A rimmed baking sheet, for toasting the bread and for carrying hot bowls in and out of the oven.
- A box grater for the Gruyère and parmesan.
Questions I Get About French Onion Soup
Why add flour to French onion soup? Two tablespoons, cooked with the onions for a minute, give the broth a little more body. Spend With Pennies leaves the flour out, so it comes down to the texture you prefer.
Can you freeze French onion soup? Yes, for up to 3 months. Freeze it without the bread and cheese, then reheat it and broil fresh toast and cheese on top.
Do I need oven-safe bowls? Yes. The bowls go under the broiler for 3 to 5 minutes, and ordinary dishes can crack from that heat.
How many slices of bread go in each bowl? One or two, depending on the size of the bowl. Spend With Pennies uses 2 slices per bowl.
More From My Kitchen
- Beef Enchiladas with Chili Gravy
- Bubbling Blackberry Cobbler
- Bubbling Blueberry Cobbler
- Buttery Classic French Toast
- Chewy Brigadeiro
- Chewy Homemade Bagels
- Chewy Oatmeal Raisin Cookies
- Chewy Peanut Butter Cookies
- Chewy Snickerdoodles
- Cinnamon Apple Muffins (with Crumb Topping)
Classic French Onion Soup
Course: SoupCuisine: American4
servings20
minutes1
hour40
minutesIngredients
4 tbsp unsalted butter
1 tbsp vegetable oil
3 lb sweet onions, such as Vidalia (about 5), halved lengthwise and thinly sliced
3/4 tsp salt
1/2 tsp black pepper
3/4 tsp sugar
1 cup dry white wine
2 tbsp all-purpose flour
6 cups beef broth
1 tsp Worcestershire sauce
1/2 tsp dried thyme
2 bay leaves
1 tbsp dry sherry
1 small baguette, cut into 1/2-inch slices
8 oz Gruyère, grated (about 2 heaping cups)
1/2 cup grated Parmigiano Reggiano
Directions
- Start the onions. Melt the butter with the oil in a large heavy pot over medium heat. Add the sliced onions, salt, pepper, and sugar, and toss until every slice is coated in fat and the pile starts to turn glossy and slump.
- Caramelize slowly. Cook over medium heat for 45 to 55 minutes, stirring now and then at first and more often as the color deepens. Scrape the brown film off the bottom each time. They’re ready when they’re deep amber, very soft, and jammy.
- Fix fast browning. If the bottom of the pot darkens before the onions have softened, stir in a few spoonfuls of water and scrape hard with a wooden spoon. The stuck film lifts back into the onions, and the pot looks glossy again.
- Reduce the wine. Pour in the wine, raise the heat to high, and cook for 8 to 10 minutes, stirring often. Stop when the liquid is nearly gone and the onions look thick and jammy, with no wine pooling around the edges.
- Cook the flour. Sprinkle the flour over the onions and stir for 1 minute. You’re done when no dry white streaks remain and the onions look lightly coated, a little pasty on the spoon.
- Simmer the soup. Add the beef broth, Worcestershire, thyme, and bay leaves and bring to a boil. Lower the heat, cover, and simmer for about 30 minutes, until the onions are silky. Fish out the bay leaves and stir in the sherry.
- Toast the bread. While the soup simmers, heat the oven to 400°F. Lay the baguette slices on a baking sheet and toast for about 10 minutes, until they’re dry and crisp all the way through and golden at the edges.
- Fill the bowls. Move an oven rack so the tops of the bowls will sit 6 inches from the broiler element, then switch the oven to broil. Set oven-safe bowls on a rimmed baking sheet, ladle in the hot French onion soup, and float 1 or 2 toasts on each.
- Broil the cheese. Pile the Gruyère and parmesan over the toast. Broil for 3 to 5 minutes, until the cheese is melted, bubbling, and golden at the edges. Let the bowls sit a few minutes before serving, because they’re extremely hot.