Heat oven 200 C / Gas 6. Toss the squash cubes in a drizzle of olive oil, season well and roast for 20 to 25 minutes, till soft.
Halfway through roasting, put the pasta on to boil.
Once the pasta is cooked, leave to one side and heat a frying pan. Add a little olive oil, the crushed coriander, cumin seeds and chilli flakes, and cook for 1 minute, stirring continuously. Note: the pan needs to be hot to release the wonderful fragrance of the spices!
Toss the pasta and roasted squash in the spice mix. Then stir through the creme fraiche and serve.