French Onion Soup Recipe | Rich Caramelised Onions & Cheesy Toasted Baguette
This classic French soup is so quick and simple to make, and you can even prepare it ahead of time — when you’re ready to eat, just warm it through and finish with your croutons. French onion soup is the ultimate comfort classic: rich, deeply savoury and built on the simple magic of slowly caramelised onions. With its golden broth, a splash of wine and plenty of melted cheese bubbling over crisp toasted bread, it feels indulgent yet wonderfully rustic.
Despite its elegant reputation, it’s surprisingly straightforward to make at home, and the long, gentle cooking transforms everyday ingredients into something truly special. Whether you’re serving it as a cosy starter or a comforting main, this French onion soup is a timeless favourite that never disappoints.
Serving Suggestions for French Onion Soup
- Crusty Baguette A classic pairing that adds crunch and is perfect for dipping into the rich onion broth
- Cheesy Croutons Melty, savoury croutons echo the soup’s flavours and make each spoonful more indulgent
- Garlic Bread Warm, buttery slices bring extra comfort and help balance the sweetness of the caramelised onions
- Cheese & Herb Scones Soft, savoury scones add a bakery-style touch and pair well with the soup’s cheesy topping.
Variations: French Onion Soup
- Red Wine & Thyme — swap white wine for red and increase the thyme for a deeper, richer broth.
- Mushroom & Onion — sauté sliced mushrooms with the onions for an earthier, more robust flavour.
- Cheddar & Mustard Boost — double the mustard in the croutons and use a mix of cheddar and Gruyère.
- Guinness Onion Soup — replace part of the stock with Guinness for a dark, malty twist.
- Vegetarian Version — use vegetable stock and add a splash of soy sauce or miso for savoury depth.
- Caramelised Shallot — replace half the onions with shallots for a sweeter, more delicate soup.
- Smoky Onion Soup — add smoked paprika or a splash of smoked Worcestershire sauce.
- Onion & Apple — add finely diced apple while caramelising the onions for subtle sweetness.
- French Onion Soup Gratinée — ladle the soup into oven‑safe bowls, top with croutons and cheese, then grill until bubbling.
- Creamy Onion Soup — stir in a splash of cream or crème fraîche at the end for a softer, velvety finish.
- Onion & Bacon — fry lardons first, remove, then caramelise onions in the rendered fat; add bacon back before serving.
French onion soup with mustard cheesy croutons
Slow‑caramelised onions simmered in a rich, golden broth, finished with toasted bread and melted cheese for a cosy, comforting bowl.
Equipment
- Large saucepan
Ingredients
- 40 g unsalted butter
- 4 large onion, halved and thinly sliced
- 1 tbsp soft brown sugar
- 1 tsp garlic paste
- 150 ml white wine
- 1 litre beef stock
- 1 tbsp thyme
- 1 bay leaf
- 1 tbsp yeast extract
- 2 tbsp cornflour, mixed with 3 tbsp water to form a thick paste
- Season with salt and pepper
Mustard cheesy croutons
- 1 french stick, cut into thick slices
- dijon mustard
- cheddar cheese
Instructions
- Heat the butter in a large saucepan over a medium heat, when the butter has melted add the onions, lower the heat and cook the onions for around 8mins until they begin to soften.
- Add the sugar and cook for another 5mins until the onions are caramelised. Then add the garlic and stir for another minute.
- Gradually add the wine and reduce by half.
- Then add the beef stock, thyme, bay leaf and yeast extract and bring to a boil
- Then add the cornflour and stir until all combined, cover and simmer for around 10-15mins.
- In the meantime, make the croutons. Preheat the grill and toast the slices on one side.
- On the uncooked side spread some mustard very thinly, sprinkle with the cheese and pop back under the grill until the cheese has melted.
- Divide the soup with into bowls, serve immediately with the croutons on the side.