This pasta is fast to make and delicious to eat! While your water is heating up and the pasta is cooking you can complete the sauce. I did the sauté-ing in steps but you can totally do it all at once if you want. First I cooked the mushrooms, then the leeks (or onions) and garlic, then I added back in the mushrooms and added the asparagus stems. I reserved the bud ends until the very end to keep them from getting overcooked.
While John was standing around waiting for the water to boil, I had him toast some pine nuts. They need special attention since they burn easily. They give the whole dish a buttery flavor when you sprinkle them on at the end.
Right before the pasta is ready add the bud ends of the asparagus to the mushrooms and asparagus stems and then add the drained pasta on top. Be sure to reserve a cup of your starchy, salty pasta water to add as well in little increments until it has made a little sauce with your vegetables. Garnish with the pine nuts, your best olive oil, and Parmesan (if you are not eating this as a vegan dish.)