Once you have put your pasta on to boil, Start straight away on the sauce.
Put your olive oil in a frying pan and once heated, brown your onions.
add the garlic and stir now and again for a few minutes (I hope your stirring the pasta), and add the mushrooms.
After about 3 minutes, once the mushrooms have shrunk , put in your cream, gradually, stirring as you add. after 2-3 more minutes, by which time your pasta should be done, strain your pasta, shaking vigorously (you don’t want any excess water.). And now all there is to be done is add the sauce to the pasta and serve!