Preheat your oven to 375°F (190°C).
In a large mixing bowl, combine your shredded or cubed cooked chicken with the crumbled bacon, condensed cream of chicken soup, milk, and ranch seasoning mix. Stir until well blended.
Pour the mixture into a greased 9x13 inch baking dish and spread it out evenly.
Arrange frozen tater tots evenly over the top of the chicken mixture.
Bake for 25-30 minutes until the tater tots are crispy.
Sprinkle shredded cheddar cheese over the top and return to the oven for another 5-10 minutes until melted and bubbly.
Let the casserole stand for a few minutes before serving.