Preheat the oven at 250° Celsius halve your pumpkin and lay it upside down onto a baking sheet. Bake in the oven for 30 up to 40 minutes or until you can easily prick the pumpkin halves with a fork. I recommend doing this step the day before cooking the sauce.
Let the pumpkin cool down, remove the flesh, put it into a mixer and add all the other ingredients on the list up to the garlic. Purée until you got a creamy smooth sauce.
While you prepare the sauce you can cook the pasta according to the instructions on the packaging.
Drain off pasta water and mix pasta immediately with the pumpkin sauce. Serve and sprinkle on some freshly chopped flat leaf parsley and nutritional yeast.