Bring a large pot of salted water to a boil and cook the pasta until al dente. Reserve 1 cup of pasta water, then drain.
Heat butter in a skillet over medium-high heat. Add mushrooms and cook without stirring for 2 minutes, then stir and cook for 5 more minutes until golden.
Pour in the cream and reduce heat to medium-low. Simmer gently for 4 minutes until the sauce thickens.
Season with salt and pepper to taste.
Add cooked pasta to the sauce and toss well. Add reserved pasta water gradually if needed to loosen the sauce.
Serve immediately with extra black pepper on top.
Notes
For best results, avoid boiling the cream and always reserve pasta water to adjust the sauce consistency. You can add chicken or shrimp for extra protein.