Cook the sausage and onion together in a skillet on the stove top set to medium high heat. Crumble the sausage. Blot the grease off the meat if desired. Set this aside.
Add half of the tater tots to the slow cooker.
Spread over the sausage onion mix over those tater tots.
Next add the remianing tater tots. (do this in a circular design).
In a large bowl, whisk the eggs, milk and seasoning.
Sprinkle over the cheese.
Pour this over the tots and sausage in the slow cooker.
Cook on LOW for 5 hours or until the center is set.
Scoop, serve and enjoy!
Notes
To get the exact amount of tater tots needed for the topping. I arrange the design in the bottom of the slow cooker FIRST, take those out and set aside. Then put the other half of tater tots down, this ensures you have the exact amount for the topping.
Instead of using cheddar cheese, you can play around with the flavors of pepper Jack cheese, mozzarella cheese, Monterey jack cheese, or shredded colby jack cheese.
Place any remaining casserole in an airtight container and store in the fridge for up to 4 days. Reheat it in the oven or microwave until warmed throughout.
Though ground breakfast sausage is the best choice for this casserole, you can use a pound of cooked and crumbled bacon or 2 cups of diced ham instead.