Bring a large pot of salted water to a boil and cook the fettuccine according to package instructions until al dente.
Meanwhile, melt the butter in a large skillet over medium heat.
Add the sliced mushrooms to the skillet and sauté until they are tender and golden brown, about 5-7 minutes.
Add the minced garlic to the skillet and sauté for an additional 1-2 minutes, until fragrant.
Pour the heavy cream into the skillet and bring it to a simmer.
Add the grated Parmesan cheese to the skillet and stir until it is melted and the sauce is smooth.
Season the sauce with salt and pepper to taste.
Drain the cooked fettuccine and add it to the skillet with the sauce.
Toss the fettuccine and sauce together until the pasta is coated in the sauce.
Serve the fettuccine with mushrooms hot, garnished with chopped parsley.