How Chefs Make French Onion Soup

French Onion Soup (my simple version)🤎 Ingredients \t•\t2 tbsp olive oil \t•\tA knob of butter \t•\t1–2kg onions, finely sliced \t•\tA few shakes of Worcestershire sauce \t•\tA few sprigs fresh Thyme \t•\tA few sprigs fresh Rosemary \t•\t1-2 litre good-quality beef stock \t•\tSalt and pepper, to taste \t•\t1 ciabatta roll, sliced and toasted \t•\tA handful of Gruyère cheese, grated \t•\tA handful of mozzarella, grated (Other additions you could add would be a splash of red wine, a bay leaf, or