Preheat your oven to 425 degrees F. Coat the inside of a 9-inch x 13-inch baking dish (or 3-quart casserole dish) with non-stick cooking spray. Set aside.
In a large mixing bowl, stir together the chicken, sour cream, ranch dressing, chicken soup, and half of the tater tots.
Pour the chicken mixture into the prepared baking dish and spread it into an even layer. Spread the shredded cheese over the filling, then top with the reserved tater tots.
Bake for 45 minutes or until the tater tots are golden brown and the filling is bubbling.
Remove from the oven and allow to cool for at least 10 minutes before serving. Garnish with green onions and/or parsley and a dollop of sour cream.
Notes
I use the meat from a rotisserie chicken for this casserole. It makes prep a breeze. You could also use 2 large chicken breasts (about 1.5 pounds) that you pre-cooked if you prefer.