01 - Bring a large pot of salted water to a boil and cook the fettuccine according to package directions until al dente. Reserve ½ cup of pasta water, then drain.
02 - Heat butter and olive oil in a large skillet over medium heat. Add sliced mushrooms and sauté for 5 to 7 minutes until golden and tender.
03 - Stir in minced garlic and cook for 1 minute until fragrant.
04 - Pour in the heavy cream and bring to a gentle simmer. Incorporate Parmesan, salt, black pepper, and nutmeg. Simmer for 2 to 3 minutes until the sauce slightly thickens.
05 - Add the drained pasta to the sauce and toss until fully coated. If the sauce is too thick, loosen with a splash of reserved pasta water.
06 - Remove from heat and stir in chopped parsley.
07 - Serve immediately, garnished with extra Parmesan cheese and additional parsley if desired.