Souper Chicken Casserole

2 cups diced, cooked chicken
1 (16 ounce) bag frozen broccoli, carrots and cauliflower,
    thawed and drained
1 can cream of mushroom soup
1/3 cup sour cream
1/4 teaspoon pepper
1 cup shredded Swiss cheese, divided
1 can French fried onions, divided

Combine all ingredients except the cheese and onions. Add one-half of the cheese, and one-half of the onions. Pour into casserole; bake uncovered, at 350 degrees F for 30 minutes.

Top with remaining cheese and onions; bake uncovered 5 minutes longer.