12 small or 6 large slices of good sourdough bread
olive oil for drizzling
2 garlic cloves peeled
Heat the oil and butter in a large heavy-based saucepan over a high heat until the butter starts to bubble.
Add the onions and sugar and fry, allowing the onions to catch slightly before turning them. This will help them caramelize, but be sure they don’t burn.
Cook for about 5minutes until they turn a dark colour, then at this point stir in the garlic.
Reduce the heat to low and cook for 30 minutes.
Add the white wine, stock and thyme and stir to combine with the onions.
Bring to simmering point and allow to cook very slowly for a further 40 minutes.
Season with salt and pepper.
Meanwhile, to make the croutons, preheat the oven to 180 degrees (350F / Gas mark 4).
Place the bread slices on a baking tray and drizzle both sides with olive oil.
Sprinkle with salt and toast in the oven for 15 minutes until golden brown.
Remove from the oven and, as soon as the toast is cool enough to tough, rub on both sides with the garlic cloves.
To serve, preheat the grill to medium. Ladle the soup into large bowls, place the crouton slices on top, sprinkle with the grated cheese and place under the hot grill until the cheese has melted and is bubbling and golden on top.