Preheat oven to 350℉. Spray a 9x13" baking pan with non-stick cooking spray and set aside.
In a large bowl, mix together soup, sour cream, cream cheese, onion powder, and salt and pepper.
Mix in the frozen vegetables and chicken.
Spread chicken mixture into the bottom of the prepared pan
In a bowl, mix crushed cracker crumbs and melted butter together then sprinkle over the top of the chicken mixture.
Bake uncovered for 30-35 minutes.
Top with parsley, if desired.
Notes
For best results, store leftover Ritz Cracker Chicken Casserole in an airtight container in the refrigerator for up to 3-4 days. For food safety, make sure to refrigerate the casserole within two hours of cooking. Reheat in the oven or microwave.