Tater Tot Breakfast Casserole

Grease a 9x13 inch casserole dish. Keep the tater tots frozen and arrange them tightly in a single layer across the bottom
Heat olive oil in a large skillet over medium to medium-high heat. Add the sausage and diced onion, and cook for 8 to 10 minutes, until the sausage is browned and the onion is tender.
Drain off any excess fat, then scatter the mixture evenly over the tater tots.
In a large bowl, whisk the eggs, heavy cream, milk, salt, black pepper, and cayenne until smooth. Fold in the shredded cheeses.
Pour the egg mixture evenly over the sausage and tater tots. Lightly press down with a spatula to ensure everything is evenly coated.
Cover the dish snugly with foil, creating a small dome so the foil does not touch the cheese.
Refrigerate for at least 1 hour and up to 12 hours to allow the tots to hydrate and the flavors to meld.
When ready to bake, preheat the oven to 350°F. Place the casserole on the center rack and bake, covered, for 40 to 45 minutes, until the edges are bubbling. Remove the foil and continue baking 10 to 15 minutes, until the top is melted, lightly golden, and the center is set.
Let the casserole stand 5 to 10 minutes before slicing. Serve warm.