You need the meat of 4 cooked, large, chicken breasts. You can either buy the boneless/skinless breasts and boil them for about 30 minutes, or (for more flavor & a little more work), buy the cheaper ones with skin and bones. Put them on a cookie sheet, drizzle with olive oil and a little salt, and bake them at about 375 for 25-30 minutes. Cool, peel off the skin, and shred the chicken. It will be very moist and tasty.
In a large casserole dish, mix the large can of cream of chicken soup, sour cream, and onion powder. Add the 4 shredded (or cubed if you prefer) cooked chicken breasts; mix well.
Bake in preheated oven (350 degrees) for about 30 minutes. Add the parmesan cheese (mix it in) and bake for another 10 minutes. This dish goes well with cooked, buttered noodles or on top of baked buttermilk biscuits, but is hearty enough to stand on its own.
You can substitute garlic powder for the onion powder, and if you want a more pronounced flavor, you can bump up the amount of the onion power a bit. This dish reheats really well too!