Preheat oven to 350°F. Lightly grease a 9x13-inch casserole dish. Pour the frozen hashbrowns into a large mixing bowl.
30 ounces frozen hashbrowns
Set a large sauté pan over medium high heat. Cook the sausage, breaking it into crumbles, until browned. Remove to a paper towel-lined plate or bowl to drain, leaving a small amount of fat in the pan.
1 pound medium spice pork sausage
Return the pan to the heat and add the diced onion and bell pepper. Cook for 3-5 minutes, until softened, then stir in the green chiles and remove from heat.
½ cup diced onion, ½ red bell pepper, 4 ounces diced green chile peppers
To the bowl with the hashbrowns, add the cooked sausage, onions, peppers, and half the cheese. Mix well to combine, then scoop into the prepared casserole dish, filling it evenly.
4 ounces sharp cheddar cheese
In another bowl, whisk together eggs, milk, parsley, salt, garlic powder, and pepper. Pour evenly over the hashbrown mixture. Scatter on the remaining cheese.
4 ounces sharp cheddar cheese, 8 large eggs, 1 cup milk, 1 teaspoon dried parsley, ½ teaspoon fine sea salt, ½ teaspoon garlic powder, ⅛ teaspoon ground black pepper
Place in the oven and bake for 50-60 minutes. Let cool for 10 minutes before serving to set.