French onion soup

Melt the butter in a large saucepan over a low heat and cook the onions for 30 minutes until softened, stirring constantly.

Add the flour, tomato puree, wine and chicken stock. Cook for a further 30 minutes. Season to taste with salt and freshly ground black pepper.

Scatter the grated cheese over the toasted French bread slices and grill until the cheese is golden and bubbling. Serve the soup immediately, with a piece of cheese topped toast floating on the top of each.