Bring a large pot of salted water to a boil. Add the tagliatelle and cook according to the package instructions until al dente. Drain and set aside.

While the pasta is cooking, heat a large pan over medium heat. Add a tablespoon of butter and the sliced mushrooms. Cook until the mushrooms are golden and have released their moisture.

Add minced garlic to the mushrooms and cook for another minute until fragrant.

Lower the heat and add the heavy cream, grated Parmesan, salt, and pepper. Stir until the sauce thickens slightly.

Toss the cooked pasta with the creamy mushroom sauce. Adjust seasoning if necessary.

Serve hot, garnished with chopped parsley and extra Parmesan cheese if desired.