Sausage Fajita Breakfast Casserole

Southern-style frozen hashbrowns (these are small cubed potatoes (and the amount is approximate))

olive oil

red bell pepper (cut into short strips)

green bell pepper (cut into short strips)

jalapeño (seeds and ribs removed, finely diced (optional))

red onion (cut into short strips)

Farmland breakfast sausage links (sliced into 1" pieces)

kosher salt (divided)

eggs

milk

garlic powder

few grinds of black pepper

Mexican blend shredded cheese

chopped cilantro for garnish (optional)