In a large skillet, brown the sausage on medium high heat, breaking up the meat as it cooks. Drain and layer into a 9x13 baking dish. Sprinkle 2 cups of the cheese evenly over sausage.
In a large bowl, whisk together the milk, eggs, pepper, onion powder, and salt until combined. Pour evenly over the cheese and sausage in baking dish. Layer frozen tater tots over the top.
If not baking right away, cover tightly with foil and refrigerate for a few hours or overnight. When ready to bake, preheat oven to 350°F/175°C. Bake, uncovered for about 35 minutes. Then top with additional ½ cup cheese, crumbled bacon, and bake another 5-10 minutes, or until bubbling and golden brown.
Garnish with green onion, let rest at room temp 10 minutes, then serve.