Cook the fettuccine or spaghetti according to package instructions until al dente. Drain and set aside, reserving 1/2 cup of the pasta water.
In a large skillet over medium heat, cook the chopped bacon until crispy, about 5-7 minutes. Remove the bacon from the skillet and drain on paper towels, leaving the drippings in the skillet.
Add the sliced mushrooms to the skillet and sauté in the bacon drippings for about 5 minutes, or until they are golden brown. Add the minced garlic and cook for an additional 1 minute until fragrant.
Pour in the heavy cream and bring to a simmer. Stir in the Parmesan cheese until melted and smooth. If the sauce is too thick, add a little reserved pasta water to reach your desired consistency.
Add the cooked pasta and crispy bacon to the skillet, tossing to combine. Season with salt and pepper to taste.
Serve immediately, garnished with chopped parsley.