Deeply caramelized yellow onions are slowly transformed into a rich, savory broth infused with Cognac, dry sherry, thyme, and bay leaf. Finished with a crusty French baguette and a bubbling blanket of Gruyère and Parmesan cheese, this Classic French Onion Soup delivers the comforting flavors of a traditional Parisian bistro. Rich, hearty, and elegant, it proves that a handful of simple ingredients can create something truly extraordinary.

Timing note: Caramelization varies with the onions and cookware. Allow longer for the optional Control Freak stages.

Ingredients

• 3 pounds (1.36 kilograms) yellow onions, thinly sliced
• 4 tablespoons (57 grams) unsalted butter
• 1 tablespoon (15 milliliters) olive oil
• 2 garlic cloves, minced
• 1 tablespoon (8 grams) all-purpose flour
• 1 tablespoon (15 milliliters) Cognac or brandy
• 1/2 cup (120 milliliters) dry sherry (not cream sherry)
• 7 cups (1.65 liters) rich beef stock
• 1 teaspoon Worcestershire sauce
• 1 bay leaf
• 2 sprigs fresh thyme
• Salt and freshly ground black pepper, to taste

For the Topping

• 1 French baguette, sliced into 1/2-inch (13 millimeters) slices
• 8 ounces (227 grams) Gruyère cheese, grated
• 2 ounces (57 grams) Parmesan cheese, grated

Instructions

1. Melt the butter and olive oil in a large Dutch oven or heavy-bottomed soup pot over medium heat.
2. Add the sliced onions and a generous pinch of salt. Cook, stirring occasionally, for 45–60 minutes until the onions become deeply caramelized and a rich mahogany brown color. If excessive fond develops on the bottom of the pot, add 1–2 tablespoons (15–30 milliliters) water and scrape the bottom clean before continuing. Reduce the heat if the onions begin to scorch.
3. Add the garlic and cook for 1 minute, stirring constantly.
4. Sprinkle the flour over the onions and cook for 2 minutes, stirring continuously to remove the raw flour taste.
5. Add the Cognac and stir to deglaze the pot.
6. Pour in the dry sherry and scrape up any remaining browned bits from the bottom of the pot.
7. Add the beef stock, Worcestershire sauce, bay leaf, and thyme sprigs. Bring to a gentle simmer.
8. Simmer uncovered for 30 minutes. Remove the bay leaf and thyme stems.
9. Season with salt and freshly ground black pepper to taste.
10. While the soup simmers, preheat the oven to 350 degrees Fahrenheit (175 degrees Celsius).
11. Arrange the baguette slices on a baking sheet and bake for 10–15 minutes, turning once, until dry and crisp.
12. Preheat the broiler and position the oven rack approximately 6 inches (15 centimeters) below the broiler element.
13. Ladle the soup into broiler-safe crocks or bowls.
14. Place enough toasted baguette slices on top of each bowl to form a nearly complete layer across the surface of the soup.
15. Combine the Gruyère and Parmesan cheeses and mound generously over the bread, allowing some cheese to reach the edges of the bowl for the classic bistro-style crust.
16. Place the bowls on a baking sheet and broil until the cheese is melted, bubbling, and deeply golden brown, about 2–4 minutes.
17. Serve immediately while piping hot.

Control Freak Induction Method

For cooks using a Breville Control Freak induction cooker, the following optional method uses the recipe’s pan-temperature settings. Watch the onions and adjust the heat as needed; cookware and onion moisture affect how quickly they brown.

Stage 1: Sweat the onions

18. Place a 5- to 7-quart cast iron Dutch oven on the Control Freak.
19. Set the Control Freak to 250 degrees Fahrenheit (121 degrees Celsius) Pan Temperature.
20. Add the butter, olive oil, onions, and a generous pinch of salt.
21. Cover and cook for 15 minutes, stirring once or twice. The onions should soften and release their moisture without browning.

Stage 2: Slow Caramelization

22. Remove the lid and increase the Control Freak to 285 degrees Fahrenheit (141 degrees Celsius) Pan Temperature.
23. Cook for 45–60 minutes, stirring every 5–10 minutes.
24. If excessive fond develops, add 1–2 tablespoons (15–30 milliliters) water and scrape the bottom of the Dutch oven before continuing.
25. Continue cooking until the onions are uniformly golden brown and greatly reduced in volume.

Stage 3: Deep Caramelization

26. Increase the Control Freak to 315 degrees Fahrenheit (157 degrees Celsius) Pan Temperature.
27. Cook for an additional 10–15 minutes, stirring frequently, until the onions reach a deep mahogany color and develop a rich, concentrated flavor.
28. Add the garlic and cook for 1 minute.
29. Sprinkle in the flour and cook for 2 minutes, stirring continuously.
30. Add the Cognac and stir to deglaze the pot.
31. Add the dry sherry and scrape up any remaining browned bits from the bottom of the Dutch oven.

Stage 4: Simmer the Soup

32. Add the beef stock, Worcestershire sauce, bay leaf, and thyme.
33. Set the Control Freak to 205 degrees Fahrenheit (96 degrees Celsius) Pan Temperature.
34. Simmer gently, uncovered, for 30 minutes.
35. Remove the bay leaf and thyme stems.
36. Season with salt and freshly ground black pepper to taste.
37. Continue with steps 10 through 17 for toasting the bread, assembling the bowls, and broiling the cheese.

Control Freak temperature summary

• Sweat Onions: 250 degrees Fahrenheit (121 degrees Celsius)
• Slow Caramelization: 285 degrees Fahrenheit (141 degrees Celsius)
• Deep Caramelization: 315 degrees Fahrenheit (157 degrees Celsius)
• Simmer Soup: 205 degrees Fahrenheit (96 degrees Celsius)

Cook’s Notes

• The onions should be deeply caramelized, not merely softened or lightly browned. This step develops the signature flavor of the soup.
• Sweeter onions may caramelize more quickly, while standard yellow onions often develop a deeper savory flavor.
• If the onions are slow to brown, add up to 1 teaspoon sugar during the last 15 minutes of cooking to encourage caramelization.
• Homemade beef stock provides the richest flavor, but a high-quality store-bought stock works well.
• For an extra-rich steakhouse-style broth, stir in 1 tablespoon (15 grams) roasted beef base when adding the stock.
• For additional depth, add 1 tablespoon (15 milliliters) balsamic vinegar along with the sherry. The vinegar will not make the soup taste sweet; it simply enhances the richness of the caramelized onions.
• Dry sherry adds complexity and depth without making the soup sweet.
• The soup base can be prepared up to 3 days in advance and refrigerated. Reheat gently before topping with bread and cheese.
• French Onion Soup often tastes even better the next day after the flavors have had time to meld.
• Watch carefully during broiling. The cheese can go from beautifully browned to burnt in less than a minute.
• Broiler-safe crocks or soup bowls are recommended for the final broiling step.

Serving Suggestions

• Serve with a crisp green salad dressed with Balsamic-Rosemary Vinaigrette.
• Pair with a roast beef sandwich, steak sandwich, or grilled cheese for a satisfying meal.
• Offer as a first course before roast chicken, prime rib, or beef tenderloin.
• Accompany with a charcuterie board featuring cured meats, cornichons, and whole-grain mustard.

Beverage Suggestions

• Dry Sherry
• Sauvignon Blanc
• Unoaked Chardonnay
• Côtes du Rhône Rouge
• Cabernet Sauvignon
• Dry hard cider
• Belgian-style Dubbel ale
• Sparkling water with lemon, or Agave Lemonade for a nonalcoholic pairing

Storage and Reheating

Refrigerate the soup base in a covered container for up to 3 days, as noted above. Store the bread and cheese separately. Reheat the base gently, then add the toasted bread and cheese and broil just before serving. Freeze the soup base without its toppings if desired.