Heat your oven to 200°C/Fan 180°C/Gas 6. Peel the squash. Halve it and scoop out the seeds. Chop into 2 cm chunks. Pop them in a bowl.
Add 2 tbsp each of the honey and brown rice vinegar to the squash with a pinch of the dried chilli flakes. Add 1 tbsp olive oil. Season with salt and pepper. Turn to coat the squash in everything.
Spread the squash out in a roasting tin. Pour over any remaining honey marinade. Bake for 30 mins till soft and a little charred.
When the squash is 10-15 mins off being ready, fill a pan with hot water. Add a pinch of salt. Bring to the boil and add the penne. Simmer the pasta for 8 mins till tender but not too soft.
While the penne is cooking, pick any thick stalks out of the watercress. Finely chop the leaves from the sage sprigs.
Drain the penne. Tip it into the roasting tin with the squash. Add the watercress and sage. Toss everything together so the watercress starts to wilt and the penne is coated in the sweet and sour juices from the pan.
Spoon the pasta into warm bowls or shallow plates. Top with spoonfuls of the cheese and serve straight away.