Onions are cooked in beef stock until soft, tender and delicious, before being topped with cheesy croutons in this simple, classic recipe. Classic French Onion Soup With Cheese Croutons Prep time: 20 mins Cook time: 40 mins Total time: 1 hour Serves: 6 Ingredients 4 Onions, thinly sliced 50g Butter 3 tbsp Plain flour 800ml