Preheat oven to 350°F (175°C) and grease a 9x13-inch baking dish.
In a large bowl, mix together the chicken, cream of chicken soup, sour cream, and half the cheese. Season with salt and pepper.
Spread the mixture evenly in the prepared baking dish.
Top with a single layer of frozen tater tots, arranging them neatly if desired.
Bake in the preheated oven for 35-40 minutes or until the tater tots are golden brown and crispy.
Sprinkle the remaining cheese on top and bake for another 5 minutes until melted.
Garnish with chopped green onions if desired, and serve warm.