Food Edition › Cook › American › Dinner › French cuisine › French Onion Soup
2 hr 15 min Intermediate Serves 6
How to · Recipe guide

How to make French onion soup.

A clear, patient guide to the dish that lives or dies by its onions. Cook them low, cook them long, and the rest almost takes care of itself — a deep, dark broth, a raft of bread, a blistered cap of cheese.

Guide byMargaux Laurent · Updated April 2026 · 8 min read
the raft, just out of the broiler
Total time
2hr 15min
Hands-on
45min
Serves
6
Difficulty
Intermediate
Before you start

A few honest truths about this soup.

French onion soup is simple to describe and hard to rush. The only real skill it asks of you is patience — you'll spend the first hour slowly coaxing sugar out of six pounds of onions. Don't try to shortcut that step. You'll know exactly why by the end.

  • A heavy, wide-bottomed pot (enamel Dutch oven is ideal)
  • A sharp knife — you're cutting a lot of onions
  • Oven-safe bowls that go under the broiler
  • Good bread, slightly stale — day-old is better than fresh
  • Beef or a rich mushroom stock (boxed is fine)
  • Dry white wine, and something to sip while you stir
Ingredients

What goes in.

Scale
6 servings
Units
  • The onions
  • 3 lbyellow onions, halved and sliced thin (about 6 medium)
  • 4 tbspunsalted butter
  • 2 tbspolive oil
  • 1 tspkosher salt, plus more to taste
  • 1 tspsugar (helps the fond along)
  • The broth
  • 1 cupdry white wine (Sauvignon Blanc)
  • 2 tbspbrandy or dry sherry
  • 8 cupsbeef stock (or rich mushroom stock)
  • 3sprigs fresh thyme
  • 2bay leaves
  • The raft
  • 6slices day-old baguette, ½-inch thick
  • 8 ozGruyère, grated
  • 2 ozComté or Emmental, grated
The key technique

Caramelize the onions slowly.

Everything else in this recipe — the wine, the bread, the cheese — is dressing. The onions are the whole dish.

When sliced onions hit low heat with fat and a pinch of salt, they give up their water. As that water evaporates, the natural sugars in the onion slowly brown — not from burning, but from a controlled Maillard reaction that builds that deep, coppery color and sweet, savory flavor.

The goal is the color of old mahogany, the texture of marmalade, and a pot that smells like it could feed a village. If the pan gets too hot, the onions will scorch instead of caramelize, so low-and-slow is non-negotiable. Stir often, but not constantly — you want a little fond to build on the bottom so you can deglaze it into the broth later.

Read more

A full guide to caramelizing onions.

If you've never done this before — or if yours usually turn pale or burnt — start with the technique page. Ten minutes of reading that saves you an hour of regret.

How to caramelize onions →

Step by step

The method.

  1. Sweat the onions, covered.

    Melt the butter with the oil in a wide Dutch oven over medium heat. Add all the onions, the salt, and the sugar. Stir once to coat, then cover and let them sweat for about ten minutes. They'll shrink dramatically — this is the point.

    10 min Medium heat

  2. Uncover and caramelize.

    Lower the heat to medium-low. Cook uncovered, stirring every few minutes, scraping the bottom of the pan. The onions will go from translucent to gold to a deep, even mahogany. This is the long part — don't rush it. If they start to darken unevenly or stick too aggressively, add a splash of water and turn the heat down.

    45–60 min Medium-low Stir often

  3. Deglaze with wine.

    When the onions are deeply browned and jammy, pour in the white wine. It will sizzle and lift all that beautiful caramelized fond from the bottom of the pan. Scrape with a wooden spoon. Let the wine reduce until the pot is almost dry.

    5 min Medium heat

  4. Build the broth.

    Add the brandy, stock, thyme, and bay leaves. Bring to a simmer and cook, uncovered, so everything mingles and reduces slightly. Taste and season — you want a broth that is dark, deeply savory, and assertive, because the bread and cheese will mellow it later.

    20–30 min Low simmer

  5. Toast the bread.

    While the soup finishes, toast the baguette slices in a 375°F / 190°C oven until dry and golden — about 8 minutes. You're not trying to brown them; you're trying to dry them so they float without disintegrating.

    8 min 375°F / 190°C

  6. Assemble and broil.

    Fish out the thyme and bay. Ladle the soup into oven-safe bowls, float a slice of bread on top of each, and cover generously with grated cheese — enough that it blankets the bread and hangs a little over the edge of the bowl. Broil on the top rack until the cheese is bubbling, deeply browned in spots, and fused to the bread as one golden raft. Serve immediately.

    3–5 min Broiler Top rack
Tips & troubleshooting

When it doesn't go to plan.

Tip

Don't stir too much.

The caramelized bits on the bottom of the pan are flavor. Stir often enough to prevent burning, but let the fond build between stirs — you'll deglaze it into the broth later.

If this happens…

The onions scorched.

The heat was too high. Start over if it's bitter; if it's only a little too dark, add a splash of water, scrape hard, and continue on lower heat. Next time, lid-on for longer.

Tip

Use day-old bread.

Fresh bread turns to paste. A slightly stale baguette will hold its shape under the cheese and give you that proper raft instead of soggy mush.

If this happens…

The broth tastes thin.

Let it reduce longer, uncovered, before assembling. Or add a single square of dark chocolate or a splash of soy — both push a thin stock toward the dark, mineral edge you're looking for.