1) Boil the potatoes for 20 minutes, drain add the milk and 100g of butter and mash well. 2) Add the cream and Parmesan to the mash and mix well. Season to taste. 3) Pour into a clean pan if necessary, cover and put to one side to keep warm. 4) Heat the olive oil in a thick-bottomed frying pan, then cook the mushrooms, a couple of handfuls at a time for 3-4 minutes until nicely coloured. 5) Add the butter, 2 remaining cloves of garlic and salt and pepper, and continue to cook for another couple of minutes then add the parsley at the last minute. 6) To serve put a dollop of mash on a plate, sprinkle over the mushrooms and serve.