Potato tart

Preheat the oven to 200 ºC and grease one medium or two smaller ovenproof dishes with a little margarine.
Boil the potatoes until done, drain and mash. Season well and add the butter and baking powder. Mix and stir in the cheese and cream.
Fry the bacon in its own fat until done, remove from the pan and chop finely,
Sauté the onions and mushrooms in the pan fat until tender. Add a little oil if necessary.
Add the bacon, onion and mushrooms to the potatoes and stir in the parsley. Turn into the prepared dish or dishes and make patterns on top of the mixture using a spoon. Dot with a little extra butter if preferred.
Bake until golden brown, about 20-30 minutes, and serve hot.
Serves 6.