There are soups you make because you have to eat something, and then there are soups you make because the weather has turned and you want the kitchen to smell incredible and you want something in a bowl that actually earns the title of dinner. A good onion soup is firmly the second kind.
Cheesy onion soup is French in origin but it belongs to anyone who’s ever stood over a pot of slowly browning onions and felt a kind of deep satisfaction at the process. Sweet, golden onions. Rich stock. Thick bread croutons soaked in the broth, piled with cheese and grilled until bubbling. And a drizzle of Wilson’s Extra Virgin Olive Oil over the top just before it hits the table. It’s one of those recipes that rewards patience and punishes shortcuts.
The Onions Are Everything in a Good Onion Soup
This onion soup lives or dies on how well you cook the onions, and how well you cook the onions depends entirely on patience. You need 45 to 50 minutes of slow, gentle heat — no rushing, no cranking up the temperature to speed things along. What you’re after is deep golden caramelisation, where the natural sugars in the onions have had time to develop into something rich, sweet and complex. That sweetness is what makes the broth taste like it’s been simmering for hours.
The trick that makes all the difference is a cartouche — a round of baking paper placed directly on top of the onions in the pot. It traps the steam, keeps the moisture in, and lets the onions braise in their own liquid rather than frying dry. Once the cartouche comes off for the final few minutes, the residual moisture evaporates and you’re left with softened, golden, intensely flavoured onions that form the base of everything that follows.
Start with a good knob of butter and two tablespoons of Wilson’s Extra Virgin Olive Oil in a large, heavy-based pot. The combination of fat matters here — the butter gives flavour and richness, and the olive oil raises the smoke point so the butter doesn’t catch before the onions are ready.
Use a Stock Worth Tasting
The broth of this onion soup is simple — stock, Worcestershire sauce, salt and pepper — which means the quality of your stock matters. Beef stock gives you the richest, deepest result and is the traditional choice. A good vegetable stock works beautifully if you prefer to keep it meat-free — just make sure it’s one with real flavour, not the watery kind. Two litres goes in, and after 15 minutes of gentle simmering, you’ll have a broth that tastes like it took all day.
A splash of Worcestershire sauce at the end adds a savoury depth that ties everything together. Taste as you go and season properly — the onions are sweet, so the broth needs to be well-seasoned to balance them.
The Cheese Makes the Crouton
The croutons are where this onion soup goes from good to memorable. Thick slices of good bread, toasted on both sides, one side buttered and spread with Dijon mustard, then piled generously with cheese and grilled until bubbling and golden. They sit on top of the hot soup, soaking up the broth from below while the cheese melts and browns above. The result is something between a crouton and a toasted sandwich, and it’s the best part of the whole bowl.
For the cheese, a mix of Gruyère and mature Cheddar is the ideal combination — Gruyère for its extraordinary meltability and nutty depth, Cheddar for its sharpness and familiarity. Woolworths stocks a good Gruyère that works beautifully here, and if you want to go full South African artisanal, Fairview’s cheese range from Paarl has options worth exploring. Don’t be shy with the quantities — you want the cheese thick enough to form a proper crust.
Finish Your Onion Soup with Olive Oil
Once the onion soup is in the bowls and the cheese is bubbling, drizzle a little Wilson’s Extra Virgin Olive Oil over each serving just before it goes to the table. It adds a fresh, peppery note that cuts through the richness of the cheese and butter, and it gives the surface of the soup a beautiful sheen. It’s the same technique French bistros use — a simple drizzle that lifts the whole dish at the last second.
This is a dish where the quality of your olive oil is actually noticeable. Wilson’s EVOO is cold-pressed, clean and peppery — it holds its own alongside the caramelised onions and aged cheese rather than disappearing into them.
Make It the Day Before
This onion soup is one of those dishes that’s genuinely better the next day. The broth deepens overnight, the sweetness of the onions mellows into the stock, and the whole thing becomes more rounded and complex. Make the soup a day ahead, refrigerate it, and reheat gently on the stove before serving. Grill the croutons fresh just before you’re ready to eat — they need to go on hot soup to soak properly — and drizzle the olive oil at the very end.
It also freezes well without the croutons, so if you’re making a big batch, hold some back in the freezer for the next cold evening that sneaks up on you.
Full recipe below: Cheesy onion soup with bubbling cheese croutons — serves 6, prep 15 minutes, cook 1 hour 15 minutes.
Cheesy Onion Soup
Ingredients
Method
- Melt the butter with the Extra Virgin Olive Oil in a large, heavy-based ovenproof pot over medium-high heat. Add the garlic and stir for a minute, then tip in all the onions. Season well with salt and pepper and stir to combine.
- Turn the heat down to low, place a cartouche (a piece of baking paper cut to fit the pot) directly on top of the onions, and cook slowly for 45–50 minutes, stirring occasionally, until deeply golden and sweet. Don't rush this step — the slow caramelisation is where all the flavour comes from.
- Remove the cartouche, pour in the stock and bring to a simmer. Add a splash of Worcestershire sauce, taste and adjust the seasoning. Simmer gently for 15 minutes to let the flavours come together.
- While the soup simmers, preheat your grill to maximum. Toast the bread slices on both sides until golden. Spread one side of each slice with a little butter and a smear of Dijon mustard.
- Slice, grate or crumble the cheese generously over the mustard side of each toast. Cut the croutons into large pieces and lay them directly on top of the hot soup in the pot, pushing them down slightly so they soak up a little of the broth.
- Grate over a little extra cheese and add another shake of Worcestershire sauce. Place the pot under the hot grill for 5–10 minutes until the cheese is melted, bubbling and golden. Watch it carefully — it goes from golden to burnt quickly.
- Ladle into bowls and finish each serving with a drizzle of Wilson's Foods Extra Virgin Olive Oil. Serve immediately.
Notes
A good onion soup earns its place in the rotation every autumn without fail. It looks impressive, it tastes like you put in far more effort than you did, and it makes the kitchen smell extraordinary for the entire time it’s on the stove. That’s a pretty good return on a bag of onions and an hour of your Friday afternoon.
Just make sure you’ve got a good bottle of Wilson’s Extra Virgin Olive Oil on hand — you’ll want it in the pot, and you’ll want it on the table.
Get the oil you need: Wilson’s Foods Extra Virgin Olive Oil is available online and in select retailers across South Africa.