French Onion Soup from Scratch

Ingredients

• 4 lbs yellow onions (about 6 large), halved and sliced 1/4-inch thick
• 4 tablespoons unsalted butter
• 2 tablespoons olive oil
• 1 1/2 teaspoons kosher salt, plus more to taste
• 1 teaspoon sugar (optional)
• 3 cloves garlic, minced
• 2 tablespoons all-purpose flour
• 1 cup dry white wine or dry sherry
• 8 cups homemade beef or chicken stock
• 4 sprigs fresh thyme
• 2 bay leaves
• 1 tablespoon brandy or cognac (optional)
• 1 baguette, sliced 3/4-inch thick
• 8 oz Gruyere cheese, grated
• 2 oz Parmigiano-Reggiano, grated
• Black pepper, freshly ground

Method

1. Slice the onions pole to pole, 1/4 inch thick and as even as you can manage. Four pounds looks absurd in the bowl. It is not — they cook down to roughly a quarter of that volume.
2. Melt the butter with the olive oil in a wide heavy pot or Dutch oven over medium heat. Add the onions and the salt and stir to coat. They will barely fit. Cover and cook 15 minutes to sweat them down and collapse the pile.
3. Uncover and drop the heat to medium-low. This is where the actual work starts. Cook 45 to 60 minutes more, stirring every 5 minutes and scraping the brown film off the bottom each time it forms. Ten-minute caramelized onions are a myth — that is a browned onion, and the soup will taste exactly like the shortcut you took.
4. Watch the stages so you know where you are: pale gold and limp around 20 minutes, amber around 40, deep mahogany and jammy somewhere between 60 and 75 minutes total. If they start sticking faster than you can scrape, splash in 2 tablespoons of water and keep going. Add the sugar only if your onions are out of season and refuse to sweeten on their own.
5. Add the garlic and cook 1 minute. Sprinkle in the flour and cook 2 minutes, stirring, to lose the raw taste.
6. Pour in the wine or sherry and scrape the bottom of the pot completely clean. Simmer until reduced by half, about 5 minutes.
7. Add the stock, thyme, and bay leaves. This is where homemade stock pays you back for the four hours — canned broth gives you a soup that tastes like salt and onions with nothing underneath.
8. Simmer uncovered 30 to 40 minutes so the flavors marry and the soup tightens slightly. Fish out the thyme stems and bay leaves, stir in the brandy, then taste and season with salt and pepper.
9. While it simmers, spread the baguette slices on a sheet pan and toast at 350°F (175°C) for 10 to 15 minutes, flipping once, until dry and crisp through. Dry bread holds its shape under the broth; fresh bread turns to paste in about a minute.
10. Heat the broiler. Set oven-safe bowls on a sheet pan and ladle in the soup, leaving 1 inch of headroom. Float one or two toasts on each and cover them edge to edge with the Gruyere and Parmigiano — take the cheese all the way to the rim so it grabs the bowl and holds.
11. Broil about 6 inches from the element for 2 to 4 minutes, until the cheese melts, bubbles, and browns in spots. Stand there and watch it. It goes from right to ruined in about twenty seconds.
12. Serve immediately, and tell everyone the bowls are dangerously hot. You earned this one over two hours — do not let it sit and go lukewarm.