Preheat oven to 350 degrees.
Spread the sausage in an even layer over the bottom of the disposable aluminum pan and cook for 30 minutes. Remove from oven and gently break any larger pieces into small bite-size pieces with a spatula. Return to oven and continue cooking until sausage is brown and cooked through, about 10 - 15 minutes more.
In a very large bowl, whisk the eggs then add 4 cups milk, onion powder, garlic powder, salt, pepper and seasoned salt. Pour into the aluminum pan containing the cooked sausage, add the cheddar cheese and mix well.
When ready to cook, When ready to bake, if baking 1 casserole in the oven move oven rack to middle position and set oven temperature to 350 degrees. If baking 2 casseroles, adjust racks evenly between top and bottom of oven. Pour mixture into the aluminum pan and arrange frozen tater tots in a single layer over the egg mixture. Sprinkle 2 tablespoons seasoned salt over tater tots.
Once oven temperature reaches 350 degrees, place uncovered casserole in oven for a bout 1 hour and 45 minutes (or 2 hours to 2 hours and 15 minutes.) Casserole is done when a knife inserted in center come out just slightly moist and casserole no longer looks soupy in the middle. Let rest at room temperature for 5 minutes then slice into 3 rows by 16 slices for 48 total pieces.