Preheat your oven to 350ºF. While the oven is heating, cook the breakfast sausage in a large skillet over medium heat until it is no longer pink. Drain any excess fat from the cooked sausage. Lightly spray a 9x13-inch pan with cooking spray to prevent sticking.

In a large bowl, toss together the frozen tater tots, cooked and drained sausage from Step 1, mozzarella cheese, and shredded cheddar cheese until evenly mixed. Pour the mixture into the prepared 9x13-inch pan. I like to distribute the cheese evenly for gooey bites throughout the casserole.

In a separate bowl, whisk together the eggs, salt, pepper, garlic powder, onion powder, and milk until well combined. Pour this egg mixture evenly over the tater tot, sausage, and cheese mixture in the pan.

Bake the casserole uncovered in the preheated oven for 60 to 70 minutes, or until the eggs are set and the top is lightly golden. I like to let the casserole sit for a few minutes after baking before serving; it helps the slices hold their shape.