Preheat the Oven to 350°F and prepare a 9-by-13-inch baking dish with nonstick spray.
Cook the sausage mixture in a skillet over medium-high heat until the sausage is no longer pink and the vegetables soften, about 6 to 8 minutes.
In a large mixing bowl, whisk together eggs, heavy cream, Dijon mustard, Tabasco, salt, black pepper, and half of the green onion tops.
Stir in 1 ½ cups of cheddar cheese and the thawed hash browns into the egg mixture, then add the slightly cooled sausage mixture.
Baking
Pour the mixture into the prepared baking dish and smooth out.
Cover with foil and bake for about 50 minutes.
Remove the foil, sprinkle remaining cheddar cheese on top, increase oven temperature to 400°F, and bake for an additional 10 to 15 minutes until browned on top.
Finishing Touches
Let the casserole rest for about 10 minutes before serving.
Garnish with the remaining green onion tops before slicing.
Notes
Can be customized with various ingredients. Store leftovers in an airtight container in the refrigerator for up to four days.