Cut pumpkin in dices. Cut the mackerel in small pieces.
Heat the oil in a large pan. Add garlic, rosemary and diced pumpkin, cook for 15 minutes over low heat. When the pumpkin is braised, coarsely smash it with a fork. Add the mackerel and cook for another 5 minutes. Deglaze with a glass of water.
Cook the Elbow Rigati Pasta in salted water following the package cooking time, drain and pour into the pan together with the pumpkin.