Start by preparing your ingredients. Finely slice the pancetta, shallots and chilli, then chop the squash into 1cm cubes. Heat 4 tablespoons of oil in a large frying pan over a medium-high heat, add the pancetta and fry for 1 minute, then stir in the shallots, chilli and rosemary leaves. Cook for a further 2 to 3 minutes, then stir in the squash and pour in the hot stock. Bring to the boil, then simmer for 20 minutes, or until the squash is tender and the liquid has reduced slightly.
Meanwhile, cook the penne in a large pan of boiling salted water until very al dente – it’ll continue cooking in the sauce so it’s important to undercook it. Reserving some of the cooking water, drain the penne and add to the sauce. Stir gently, adding a splash of the cooking water to loosen, if needed, then cook for a further 2 minutes to let the penne soak up all those beautiful flavours. Finely grate in the Parmesan and stir until deliciously creamy. Serve with a twist of pepper and an extra grating of Parmesan.