Classic French Onion Soup with Gruyère Croutons
Ingredients
For the Soup:
6 Onion (yellow)
55 g Butter (unsalted)
125 ml Red wine
30 ml Brandy or Cognac
1 L Chicken stock prefer a good quality one- 1 L Beef stock prefer a good quality one
1 tbsp Flour (plain)
1 pinch Nutmeg (ground)
Salt
Black pepper
For the Crouton Topping:
- 8 slices Baguette
1 Garlic clove
200 g Gruyère cheese (grated)
Instructions
- Peel the onions. Slice them in half from root to tip, then lay them flat-side down. Slice them into thin half-moons.
- In a large, heavy-based pot or Dutch oven, melt the butter over a medium-low heat. Add all the sliced onions and a pinch of salt. Cook, stirring occasionally, for about 45 minutes to 1 hour. Do not rush this step. The onions should become very soft, deeply golden brown, and sweet as they caramelise. If they stick, add a splash of water.
- Once the onions are caramelised, increase the heat to medium-high. Add the red wine and brandy, and use a wooden spoon to scrape up any browned bits from the bottom of the pot. Let the liquid bubble and reduce by half. Sprinkle the tablespoon of flour over the onions and stir constantly for 1-2 minutes to cook out the raw flour taste.
- Pour in both the chicken and beef stocks, and add the pinch of nutmeg. Bring to a boil, then reduce the heat and simmer gently, uncovered, for 30-40 minutes. The soup will reduce slightly and the flavours will meld. Season well with salt and pepper to taste.
- While the soup simmers, preheat your grill (broiler) to high. Slice the baguette into 12 rounds, about 1.5cm thick. Toast them under the grill or in a toaster until crisp and golden. While still warm, rub one side of each toast lightly with the cut side of the garlic clove.
- Place four ovenproof soup bowls or crocks on a sturdy baking tray. Ladle the hot soup into the bowls, filling them nearly to the top. Place 2-3 garlic-rubbed toasts on the surface of each soup to cover it. Divide all the grated Gruyère cheese evenly over the top of the toasts, letting some fall into the soup.
- Carefully place the baking tray under the hot grill. Grill for 3-5 minutes, watching closely, until the cheese is completely melted, bubbling, and spotted with dark golden brown.
- Let the soups cool for a minute or two (the bowls and cheese will be extremely hot) before serving immediately.
Notes
FAQs
Why does it take so long to caramelize the onions? Can I speed it up?
True caramelization is a slow chemical process, not just sautéing. Rushing it with high heat will burn the sugars, leaving you with bitter, scorched onions instead of deep, sweet, umami-rich flavour. The 45-60 minute commitment is the soul of the soup. Put on some music and stir occasionally.
Is it necessary to use both chicken and beef stock?
For the most authentic, deeply savoury flavour, yes. The combination provides a richer, more complex base than either stock alone. For a vegetarian version, use an excellent, dark vegetable stock, but be prepared for a lighter, albeit still delicious, result.
Can I use a different cheese?
Gruyère is non-negotiable for its superb melting quality, nutty flavour, and perfect golden-brown crust. Comté is a fine substitute. Do not use Emmental (too bland and stringy) or a generic “pizza blend.” The cheese is half the experience.
What type of onions are best?
Use large yellow or brown onions. They have the ideal sugar content for caramelizing. Avoid sweet onions (like Vidalia), which can become cloying, and red onions, which will discolour the soup. White onions can work in a pinch.
My cheese slides off the crouton into the soup. How do I prevent this?
Two tips: 1) Ensure your toasted baguette slices are completely dry and crisp so they act as a raft. 2) Place the toasts on the soup just before grilling – don’t let them sit and soak. Cover them generously with cheese, letting some fall onto the soup’s surface to act as “glue.”
Can I make the soup base ahead of time?
Absolutely, and it often tastes better the next day. Complete the soup through the simmering step. Cool, then refrigerate for up to 3 days. Reheat gently before assembling with croutons and cheese. The flavours improve as they meld.
Do I need special ovenproof bowls?
Yes. The bowls must be able to withstand the intense heat of the broiler/grill. Traditional French onion soup crocks, ramekins, or any ceramic bowl marked as oven-safe are essential. Do not use standard soup bowls or anything with metal trim.
Is the brandy/cognac essential?
It adds a subtle, sophisticated depth that rounds out the flavour. If you don’t have it, you can omit it and use a little extra red wine. Do not substitute with a sweet liqueur.
How do I store and reheat leftovers?
Once assembled and grilled, it’s best eaten immediately. If you have leftover soup base (without croutons/cheese), store it as above. Leftover fully assembled soup will be soggy. For a single serving, you can reheat the base, top with a fresh crouton and cheese, and broil.
What’s the best wine to use for deglazing?
Use a dry, drinkable red wine like a Pinot Noir, Côtes du Rhône, or a Cabernet Sauvignon. The rule is: if you wouldn’t drink a glass of it, don’t cook with it. Avoid “cooking wine,” which is overly salted.
This was so easy to make and super tasty! You have to trust the recipe and take your time. I did use grated emmental instead of gruyere and it was still nice but very stringy indeed!