Preheat oven to 350°F (175°C) and grease a 9x13-inch baking dish.
If using raw chicken, poach or roast and shred; cool slightly before using.
In a large bowl combine cream of chicken soup, sour cream, mayonnaise, and half the shredded cheddar cheese.
Stir in minced garlic, diced onion, parsley, onion powder, garlic powder, salt and pepper until smooth.
Fold in shredded chicken and optional thawed vegetables until evenly coated.
Spread the chicken mixture into the prepared baking dish, smoothing the top.
Sprinkle the remaining cheddar evenly over the casserole.
Crush the potato chips lightly and toss with melted butter; spread chips over the cheese layer.
Bake uncovered for 25–30 minutes, until sauce is bubbly and topping is golden brown.
Let the casserole rest 5–10 minutes before serving to set and make slicing easier.