Spray a large frying pan with low-calorie cooking spray and place over a medium heat. Add the onion and garlic and fry gently for 5 minutes, until softened a little.
Add the mushrooms and cook for 8-10 minutes, until the onion and mushrooms have softened and are lightly golden.
Add the chicken breasts and cook for 2-3 minutes on each side to lightly brown. Pour in the chicken stock and simmer over a medium heat for 10 minutes. Turn the chicken over and partially cover with a lid. Simmer for a further 10 minutes, or until the chicken is cooked, shows no sign of pinkness and the juices run clear.
Remove from the heat and stir in the cream cheese until completely blended. If the sauce is too thin, keep simmering, uncovered, to reduce to your liking. If the sauce is too thick, add a little water and stir in.
Return to the heat and stir in the Parmesan, sweetcorn and spring onion. Continue to simmer, uncovered, for 4-5 minutes, until the spring onion is tender. Season to taste with salt and black pepper if needed. Serve with a small portion of basmati rice or other accompaniment of choice.