Heat olive oil in a large pot over medium heat. Sauté onion until translucent, about 5 mins. Add garlic and cook 1 min.
Add broth, pasta, salt, and pepper. Boil, then simmer until pasta is cooked and most liquid is absorbed, 10-12 mins.
Stir in heavy cream and lemon juice, butter and parsley. Mix in shredded Parmesan.
Serve topped with Parmesan shavings.
