Preheat Oven: Preheat oven to 400 degrees F (204 degrees C). Pull out and set aside a 9x13-inch baking dish.
Mix Together Base: To a large mixing bowl, add canned soup, milk, garlic powder, onion powder, and red pepper flakes. Mix together until combined. Then, stir in shredded chicken and frozen corn.
Assemble in Baking Dish: Transfer mixture to baking dish. Sprinkle 1 cup of cheese on top, then arrange tater tots in a single layer (you may have a few tater tots left over).
Bake: Transfer baking dish to oven and bake until bubbling, which will take about 30-35 minutes. Remove baking dish from oven, sprinkle remaining ½ cup shredded cheese on top, return dish back to oven and bake until cheese has melted, about 5 additional minutes. Optionally, transfer baking dish to top oven rack, turn on oven broil, and broil until cheese on top is golden, about 1-2 minutes; watch carefully to avoid burning.
Garnish and Serve: Remove casserole from oven and allow to cool for a few minutes before, optionally, garnishing with chopped parsley and green onions or chives, then serving.