Clean and slice the mushrooms. In a large sauté pan or skillet over medium heat, melt the butter. Add the mushrooms and stir to coat. Add the salt and pepper and sauté the mushrooms until they start to release their juice again and get some color – about 5 minutes, stirring occasionally.

Add the wine and turn the heat up to medium high. Cook until the wine has been absorbed/evaporated. Set the mushrooms aside.

To a large mixing bowl, add the butter slices. Bring a large pot of water to a hard boil and add enough salt so that the water tastes like the ocean (2 tablespoon of salt for 6-8 quarts of water). Add the fettuccine and cook until al dente (for fresh homemade pasta, this takes about 90 seconds; for store bought dried pasta, follow package instructions).

Once al dente, remove the pasta from the pot using tongs or a pasta spoon and immediately place the hot fettuccine into the large mixing bowl with the butter. Using a rubber spatula or wooden spoon, mix, stir, and flip the pasta to incorporate the butter. Add some of the hot pasta water – about ¼ cup at a time – to increase the creaminess until the butter is melted completely and there is a nice creamy butter sauce in your bowl. You have made a sauce with the butter and starchy water at this point.

Once the butter is fully incorporated, add the cheese a little at a time and continue to mix. You will probably have to add another ladle of water and continue to stir until the cheese melts. Taste for seasoning and adjust with a pinch of salt if needed. Because the pasta water is salted and Parmesan cheese is generally salty, make sure you add salt AFTER you taste.

Finally, add the mushrooms and their juices and mix thoroughly. Serve and garnish with additional Parmesan, crushed red pepper flakes and/or parsley or fresh basil.