Cook the Fettuccine Start by bringing a large pot of salted water to a boil. Once boiling, add the fettuccine pasta and cook according to the package instructions, usually about 8-10 minutes until al dente. Drain the pasta, reserving a little bit of pasta water for later if needed to loosen the sauce, and set it aside.
Sauté the Mushrooms While the pasta cooks, heat the olive oil and butter in a large skillet over medium heat. Once the butter has melted, add the sliced mushrooms. Sauté the mushrooms for about 5-6 minutes, stirring occasionally, until they are golden brown and tender. The mushrooms should release some moisture and cook down to a deep brown color.
Add Garlic and Cream Add the minced garlic to the skillet and cook for another minute until fragrant. Pour in the heavy cream and bring the mixture to a gentle simmer. Stir in the Parmesan cheese, allowing it to melt into the sauce. Season with salt and pepper to taste, adjusting the seasoning as needed. If the sauce is too thick, add a little of the reserved pasta water to achieve your desired consistency.
Toss the Pasta in the Sauce Add the cooked fettuccine pasta to the skillet, tossing it well to coat with the creamy sauce. Allow the pasta to simmer in the sauce for 1-2 minutes, so it absorbs the flavors. Make sure the pasta is well-coated with the creamy mushroom Alfredo sauce.
Serve and Garnish Once everything is well combined, serve the Mushroom Alfredo Fettuccine hot, garnished with freshly chopped parsley and extra Parmesan cheese if desired. The parsley adds a touch of color and freshness, balancing the richness of the sauce.