Classic French onion soup

Method

1. Melt the butter in a large frying pan with a good splash of olive oil, then gently fry the onions, finely for 10 minutes. Season with salt and pepper, cover with a lid and fry very gently for 30-40 minutes. Remove the lid and fry for a further 15 minutes until really soft and golden brown.
2. Tip the caramelised onions into a large saucepan with the thyme sprigs, then add a good splash of calvados and the white wine. Simmer for 10 minutes, then add 1.5 litres fresh beef stock. Simmer for a further 30-40 minutes.
3. Meanwhile, heat the grill. Top the baguette slices with the grated gruyère, then melt under the grill. Serve the soup with the toasts on top and extra grated gruyère.