Brush the gratin dish with butter.
Cook the pasta in boiling salted water for approx. 4 mins., drain, transfer to the prepared dish.
Peel and finely chop the onion, press the garlic. Heat the oil in a frying pan. Brown the meat for approx. 5 mins. per batch. Remove, season. Reduce the heat, sauté the onion and garlic in the same pan, add the tomato puree, cook briefly. Add the stock, bring to the boil, then simmer for approx. 5 mins. Return the meat to the pan, bring to the boil once more, spread on top of the macaroni, mix together.
Cheese and apples
Roughly grate the cheese. Cut the apples in half, core and slice the apples. Spread the cheese and apples on top of the gratin.
Approx. 30 mins. in the centre of an oven preheated to 180°C.