In a large pot on medium high heat add olive oil, garlic and onion. Sauté for 2-3 minutes or until onions are translucent. Add mushrooms. Sauté for an additional 2-3 minutes.
Add some salt, pepper, and broth. Bring to a boil and reduce heat to low.
Now add your creamy goodness, which is the heavy cream, and sour cream. Stir in the cooked pasta and grated parmesan cheese. Give everything a good stir. Let sit for a few minutes to really thicken.
Taste and check for seasonings. Garnish with parmesan cheese shavings!