Preheat your oven to 375°F and lightly coat a 9x13-inch baking dish with nonstick spray.
In a large bowl, combine the shredded chicken, cream of chicken soup, sour cream, milk, ranch seasoning, black pepper, and 1 cup of the Colby Jack cheese. Stir until the mixture is evenly blended.
Spread the chicken mixture evenly across the bottom of the prepared baking dish, ensuring it reaches the edges.
Sprinkle half of the crumbled bacon over the chicken layer.
Neatly arrange the frozen tater tots on top of the casserole.
Bake in the preheated oven for 30 minutes, or until the tater tots turn golden and crispy.
Remove the dish from the oven and evenly scatter the remaining ½ cup of cheese over the tater tots. Place back in the oven and bake for an additional 10 minutes, allowing the cheese to melt.
Once out of the oven, top with the rest of the crumbled bacon and garnish with sliced green onions before serving.