Preheat the oven to 350°F. Butter a 9 × 13-inch casserole dish.

Heat a skillet over medium-high heat and add the avocado oil. When hot, add the breakfast sausage. Cook for 7–8 minutes, breaking it into crumbles, until cooked through. Remove from the heat and let it cool slightly.

In a large mixing bowl, whisk together the eggs, milk, Italian seasoning, garlic powder, kosher salt, and black pepper. Stir in the cheddar cheese.

Pour the egg mixture into the prepared casserole dish. Sprinkle the sausage evenly over the egg mixture, then arrange the tater tots on top.

Bake on the middle rack for 50 minutes to 1 hour, until the eggs are set and no liquid egg remains.

Let the casserole rest for 5 minutes before serving. Add sour cream, hot sauce, and scallions if desired.