Preheat oven to 350°.
Combine first 5 ingredients in a large bowl, stirring well. Pour chicken mixture into a 13- x 9-inch baking dish coated with cooking spray.
Combine baking mix, milk, and sour cream in a medium bowl; spoon over chicken mixture.
Bake, uncovered, at 350° for 50 to 60 minutes or until topping is golden. Serve immediately.