Heat the oil and butter in a large saucepan over low heat. Add the onion and thyme and cook for 20 minutes or until softened and caramelised. Gradually add the wine, scraping the base of the pan with a wooden spoon. Cook for 1 minute. Add the stock and pepper, increase the heat to medium and cook for 15 minutes. Sprinkle the bread with the cheese and place on a baking tray. Grill (broil) under a preheated hot grill for 2–3 minutes or until the cheese is melted and golden. Serve with the soup.