Cook the pasta according to the package instructions until it is al dente. Reserve about 1/2 cup of pasta water, then drain the pasta and set it aside.
In a large skillet heat 1 tbsp oil and 1 tbsp butter together at medium-high temperature. Season the thinly sliced chicken with salt and pepper. When the pan is hot and the butter melted fry the chicken until browned and cooked through about 2 minutes on each side. Take cooked chicken out of the pan and set aside.
In the same pan add 1 tbsp oil and cook the onion until lightly browned, about 2-3 minutes. Add the sliced mushrooms and cook until tender, about 2 minutes.
Add white wine to the pan and let simmer until reduced by half.
Add chicken stock and cream. In a small bowl combine cornstarch and water. Stir until starch is completely dissolved, take the pan off the heat then add to the sauce. Bring to a boil and let simmer without a lid at high heat for about 2-3 minutes to reduce and thicken.
Add the cooked chicken back to the pan and cook for 30 more seconds.
Add pasta water if needed. Stir in parsley and season to taste with salt and pepper.
Serve over pasta.