Bring a large pot of salted water to a boil. Add the pasta and cook according to package instructions until al dente. Reserve 1 cup of pasta water, then drain the pasta and set aside.
In a large skillet over medium heat, add the chopped bacon. Cook until crispy, about 5-7 minutes. Remove the bacon from the skillet and drain on paper towels, leaving the bacon fat in the skillet.
In the same skillet, add the olive oil, diced onion, and sliced mushrooms. Sauté until the onions are translucent and the mushrooms are tender, about 5 minutes.
Add the minced garlic to the skillet and cook for an additional minute until fragrant.
Pour in the heavy cream and stir to combine. Bring to a simmer and let it cook for about 3-4 minutes until the cream thickens slightly.
Stir in the grated Parmesan cheese, cooked bacon, and reserved pasta water as needed to reach the desired sauce consistency. Mix until well combined.
Add the cooked pasta to the skillet, tossing to coat the pasta in the creamy sauce. Season with salt and black pepper to taste.
Serve hot, garnished with fresh chopped parsley.