Preheat the oven to 350°F and lightly spray a 9x13-inch baking dish with cooking spray; set aside.
Cook the angel hair pasta according to package directions until al dente, then drain thoroughly.
In a large bowl, combine the chopped cooked chicken, cream of chicken soup, sour cream, onion powder, garlic powder, and the undrained can of Rotel; stir in 1/2 cup of the shredded cheddar cheese.
Add the drained pasta to the chicken mixture and toss gently to combine; spread the mixture evenly into the prepared baking dish.
Sprinkle the remaining 1 1/2 cups shredded cheddar cheese over the top, then evenly distribute the French fried onions over the cheese.
Bake uncovered for 25 to 30 minutes, until the casserole is bubbly and the topping is golden; remove from oven and let rest a few minutes before serving.
