Preheat oven to 400 degrees. In a large bowl, whisk together sour cream, chicken broth, Dijon mustard, and black pepper until smooth.
Add rice, chicken, ham, Swiss cheese and frozen peas. Stir to combine. Pour mixture into a 13 x 9 baking dish and spread evenly.
In a small bowl, mix together crushed corn flakes, Parmesan cheese and melted butter. Spread evenly over top of casserole. Baked uncovered on center rack for 25 minutes, until heated through and topping is golden brown.