Prepare pasta following the direction on pasta package.
Saute onions, mushrooms and garlic in 1 tablespoon of the butter until tender. Remove the onions, mushrooms and garlic and set them aside.
In the same pan, cook the chicken, stirring frequently. Remove the chicken and set aside until later.
To the same pan, add 2 tablespoons butter and melt over a low-medium heat. Sprinkle the flour over the butter and stir to make a roux. Slowly add in the wine, water and heavy cream, stirring constantly. Cook over a medium heat until thickened, stirring often. Add the parsley and let simmer for a few minutes.
Add the chicken, mushrooms, garlic and onions back in and simmer for 2 more minutes. Pour over the pasta and server with Parmesan cheese.