(1) Preheat oven to 180 °. Put the potatoes in a large volume of cold water. Bring to a boil and cook until you can plant a knife easily into potato. (2) Meanwhile, finely chop the onion, then FRY it in a hot skillet with a tablespoon of olive oil, until it becomes translucent. Add the chopped meat, salt and pepper to your liking and let return to low heat. (3) When the meat is almost cooked, add tomato paste and simmer a few minutes. Book warm. (4) When the potatoes are cooked, peel them and then crush them using a press puree or a fork. Add the soft butter into parcels and return to cook on low heat stirring continuously. Gradually stir the cream and parmesan. The puree should be smooth, to the need to add milk to relax. ((5) Put ground meat in a gratin dish or small individual dishes) and then top with mashed potatoes. Sprinkle with grated cheese and bake for 10 minutes. Once this time is up, go your oven in grill mode and let yet 5 minutes to Brown the cheese. Serve with green salad.