Preheat the oven to 200°C (Fan 180°C), Gas Mark 6 and grease a 35 x 20cm oven-proof dish.
Heat the Mash Direct Cauliflower Cheese Gratin in a hot oven for 10 minutes.
Bring a large pan of salted water to the boil and stir in the macaroni. Cook for 10 minutes, or until al dente, drain well.
Heat olive oil in a large frying pan and cook the onion until soft, then add the pancetta and cook until crisp. Stir in cream and bring to a boil, then remove from the heat and stir in mozzarella, macaroni and Cauliflower Cheese Gratin and pour into the oven-proof dish.
Mix the breadcrumbs with the Parmesan and scatter over the top.
Bake for 25–30 minutes, or until golden and bubbling.