Place chicken pieces in a 9x13 inch baking dish. Season chicken with garlic powder, salt, pepper and poultry seasoning.
In a large bowl combine the sour cream, cream of chicken soup and cream of mushroom soup. Mix well with a wire whisk. Add the wine and mix together. Pour this cream mixture over the chicken and bake in the preheated oven for 40 minutes.
Add the onion and mushrooms and stir into the chicken/sauce mixture. Bake for another 30 minutes. Let cool 10 minutes and serve.
