In a large skillet, cook breakfast sausage over medium heat until browned and crumbled. Drain excess grease and let cool.
Spray a 9x13-inch baking dish with cooking spray. Arrange frozen tater tots in a single layer on the bottom.
Sprinkle cooked sausage evenly over the tater tots, then top with shredded cheddar cheese.
In a large bowl, whisk together eggs, milk, sour cream, garlic powder, onion powder, salt, and pepper until smooth.
Pour egg mixture evenly over the entire casserole, making sure it seeps down between the tater tots.
Cover tightly with plastic wrap and aluminum foil. Freeze for up to 2 months, or bake immediately.
To bake from frozen: Thaw in refrigerator overnight. Let sit at room temperature for 30 minutes. Preheat oven to 350°F.
Remove plastic wrap, cover with foil, and bake for 40 minutes. Remove foil and bake an additional 10 minutes until tater tots are crispy and eggs are fully set.
Let stand 5 minutes before serving. Top with sliced green onions and serve with salsa or hot sauce if desired!