In a large skillet, heat olive oil over medium-high heat. Add bacon pieces and cook until light brown but not crisp. Remove bacon from pan and set aside. Do not clean pan.
Add mushrooms and garlic to pan. Toss/stir around and cook over medium-high heat for 5 minutes; increase heat to high if needed to help mushrooms begin to turn golden brown.
Pour in chicken broth. Stir, scraping the bottom of the pan to loosen any bits. Cook over medium-high heat for several minutes, or until the liquid is reduced by half.
Reduce heat and pour in half and half and cream. Stir and allow to bubble and thicken for a couple of minutes. Add sliced green onions parsley and bacon, then cook for one more minute. Finally, add Parmesan and stir, allowing cheese to melt and incorporate into the sauce. Turn off heat.
Add cooked pasta to a large bowl. Add half the sauce from the pan. Toss with tongs.
Add 1/2 cup hot pasta water at this point if the pasta mixture is too thick and gunky. Toss and add more water until it reaches the consistency you need.***
Serve pasta in individual bowls, topping each helping with the rest of the sauce. Sprinkle with extra parsley and extra Parmesan.