Cook pasta according to package directions. To ensure your pasta does not overcook, check for doneness several minutes before the package directions specify, and then every minute or so.
Drain in a colander and rinse under cold water. Set aside.
Heat a medium saucepan over medium heat. When the pan is hot, add 2 tablespoons of water followed by the mushrooms.
After 2 minutes of cooking, add the garlic.
Cook until the mushrooms are soft, and most of the liquid has evaporated. About 6 minutes.
Add the alfredo sauce.
When the sauce just comes to a simmer, add the pasta.
Stir and heat through.
Return to the chicken. Slice against the grain and serve over pasta alfredo.
Sprinkle each serving with 1 tablespoon of parmesan cheese and garnish with the Italian parsley, if desired.