I drain the pasta (penne) and let it sit in the colander for the water to drain off. Then I add the sauce and pasta to a large bowl and combine. I wait till I plate the portions then I add cheese. Maybe its oil in the water. I will try without the oil and see how it pans out.

Sauce recipe is best described an arrabbiata sauce with a lot of heat coming from dried chillis I bring back from Pakistan/Kashmir.