Preheat the oven to 350°F.

Heat a large skillet over medium-high heat and add the chorizo, breaking it up with a spoon. Cook the sausage until it is browned and no longer pink, about 6-7 minutes. Using a slotted spoon, transfer the chorizo to a paper towel-lined plate to drain, reserving about 1 tablespoon of grease in the pan.

Return the skillet to medium-high heat and add the onion and bell pepper. Cook until the onion is tender and translucent, about 5-6 minutes. Stir in the can of chiles, then remove the skillet from heat and allow it to cool.

Meanwhile, beat the eggs, milk, salt, oregano, garlic powder, and black pepper together in a large mixing bowl.

Lightly grease a 9x13-inch baking dish with cooking spray. Layer the frozen shredded potatoes on the bottom of the dish. Crumble in the chorizo, then add the onions and peppers. Evenly pour in the egg mixture, then top with the cheese and green onions.

Bake for 35-40 minutes until the eggs have set and a knife comes out clean when inserted into the middle of the casserole. Allow the casserole to rest for 10 minutes before serving.