Preheat the oven to 375°F (190°C) and grease a 9×13-inch baking dish.
Cook the chorizo in a skillet until browned. Add the onion and pepper, then cook for another 4 minutes.
Whisk the eggs, milk, garlic powder, cumin, salt, and black pepper in a mixing bowl.
Spread the potatoes and chorizo mixture in the dish. Add most of the cheese, then pour the eggs over the top.
Sprinkle with the remaining cheese and bake for 40 to 45 minutes, until the center is completely set.
Rest for 10 minutes and add cilantro if desired. Cool individual servings fully before freezing.
