Cook the spaghetti in salted water according to the instructions on the package. Then put in a sieve and drain well.
For the sauce, roast the chopped onion in a little oil. Add the diced pumpkin flesh and the diced bell pepper and roast briefly. Pour in the vegetable stock and season with curry powder, nutmeg, chili powder, salt and pepper. Cover and simmer gently for about 5 - 10 minutes (depending on the size of the pumpkin cubes). The pumpkin should be soft but still bite. Then stir in the crème fraîche and let it boil down a little. Finally add the drained spaghetti and mix everything together well.