Step 1

Heat a large skillet over medium-high heat. Cook and stir sausage in the hot skillet until browned and crumbly, 5 to 7 minutes. Remove from heat and let cool slightly, about 5 minutes. Transfer to a large bowl.

Step 2

Add hash browns, ham, Monterey Jack cheese, dry mustard, and onion powder to sausage; mix to combine. Pour loosely into a greased 9x13-inch baking pan. Whisk eggs, evaporated milk, half-and-half, salt, and pepper together in a large bowl. Pour evenly over the hash brown mixture, cover with aluminum foil, and refrigerate, 8 hours to overnight.

Step 3

Pull from the refrigerator 30 minutes prior to cooking. Add Cheddar cheese and recover.

Step 4

Preheat the oven to 350 degrees F (175 degrees C).

Step 5

Cook in the preheated oven for 45 minutes. Remove foil and continue to cook, uncovered, until cheese is bubbly, 15 to 20 minutes more. Let stand for 10 minutes to firm up before serving.