Bake cornbread mix according to package directions, adding 1/2 cup corn to the batter. Let cool and then crumble. This step can be done a day in advance.
Butter a 9X11-inch baking dish. Set aside.
In a medium bowl, mix together sour cream, lemon juice, Worcestershire sauce, celery, onion, garlic powder, red pepper flakes, black pepper, and salt.
Coat each chicken breast in the sour cream mixture and place in prepared dish. Pour remaining sour cream mixture over the chicken. Cover with plastic wrap and refrigerate for 1 hour.
Preheat oven to 350 degrees.
In a medium bowl, toss the cornbread crumbs with poultry seasoning and melted butter.
Remove chicken from refrigerator, top with cheddar cheese and then cornbread crumbs. Cover with foil and bake for 45 minutes. Uncover and bake another 10 minutes.
Notes
Make the cornbread a day in advance to cut down on preparation time and give the cornbread time to get a little stale.