Preheat the oven to 200°C (400°F). Tear the mozzarella and leave it on a piece of kitchen paper to drain while you make the sauce.

Bring a large pot of water to the boil, salt it generously and cook the rigatoni for 2 minutes less than the packet instructions. Drain and set aside.

Meanwhile, heat the olive oil and butter in a large, deep pan or Dutch oven over medium heat. Add the chicken, season with salt and pepper, and cook for 5-6 minutes until golden and cooked through. Remove the chicken from the pot and set aside.

Add the onion and mushrooms and cook for 6-7 minutes over medium heat, until the mushrooms started to colour.

Stir in the garlic and cook for a further minute, then add the tomato paste and cook for another minute until the paste darkens slightly.

Pour in the chicken stock and the tomato sauce, add the torn basil, and simmer for 5 minutes until slightly thickened.

Lower the heat, stir in the half and half and a third of the Parmesan, then add the spinach and cook for 1-2 minutes until wilted. Return the cooked chicken to the pot and season to taste.

Add the drained rigatoni to the pan and toss until everything is well coated.

Transfer to a baking dish. Scatter over the torn mozzarella and the remaining Parmesan.

Bake uncovered for 20-25 minutes, until bubbling and golden at the edges. Let it rest for 5 minutes before serving.