Start this recipe by making up the mushroom soup. Tip the dried soup into a small saucepan and stir in the 900ml cold water. Heat gently on a medium heat, stirring constantly until the soup thickens and just begins to boil. Remove off the heat and put aside. Next, heat the butter and oil in a frying pan and sauté the onion and garlic together for 2 minutes. Add in the fresh thyme and chicken mince and brown for 2 minutes. Add in the Arborio rice and coat with the juices in the pan, cooking for just a minute or two. Pour in the white wine and evaporate. Transfer the mixture to an ovenproof oven dish and sprinkle over the sliced mushrooms. Pour over the prepared mushroom soup and mix lightly with a spoon. Cover with a tightly fitting lid or with tin foil and bake for 25-30 minutes until just cooked. It is important that you mix the rice once during the cooking time. When ready, remove the baked rice from the oven and stir in the mascarpone. Sprinkle over the Parmesan cheese and serve immediately.