1. Preheat and Prep
Set your oven to 350°F (175°C). Spray the baking dish lightly with cooking spray to prevent sticking.

2. Cook the Sausage
In a large skillet over medium heat, crumble in the hot breakfast sausage. Cook until no pink remains and the meat is crumbly. Drain off any excess fat, then spread the sausage evenly across the bottom of the prepared casserole dish.

3. Season and Layer Tots
Sprinkle the salt, pepper, garlic powder, and onion powder over the sausage. Arrange the frozen tater tots in a single layer on top of the sausage, ensuring full coverage so each bite has that crispy potato texture.

4. Add the Cheeses
Evenly distribute the shredded cheddar across the tater tots, then sprinkle on the mozzarella. The dual cheeses provide both sharp flavor and gooey melt.

5. Whisk the Custard
In a separate bowl, crack in eight eggs and pour in two cups of milk. Whisk vigorously until the mixture is smooth and homogenous.

6. Combine and Bake
Carefully pour the egg-milk mixture over the layered sausage, tots, and cheese. Give the dish a gentle shake on the counter to help the custard settle. Slide the casserole into the oven and bake for 55 to 60 minutes, or until the eggs are fully set and the top is golden brown. When you insert a slim knife into the center, it should emerge without any wet batter clinging to it.

7. Rest and Serve
Let the casserole rest for five to ten minutes on the countertop. This brief cool-down firms the custard slightly, making it easier to slice. Serve warm, either directly from the dish or plated individually.