My parents always made some type of "breakfast casserole" around holidays. Easter, Thanksgiving, Christmas, you know. It usually had some cubes of bread, eggs, milk, sausage. It was delicious. I've taken that idea and adapted it a little bit to add hash browns instead of bread cubes. It's an awesome upgrade. —Brussels Sprouts for Breakfast
Start with the sausage. In a large saute pan, heat a little olive oil over medium-high heat. Add sausage, with casing removed. Break up with a wooden spoon as it cooks, so that it is in bite sized pieces. Let cook for 7-8 minutes, until mostly browned. Remove with a slotted spoon to a mixing bowl.
Lower heat to medium, and add olive oil only if there isn't enough oil left in the pan from the sausage (there is probably more than enough). Add onion, poblano, salt and pepper and cook for 5 minutes. Remove to the same mixing bowl as the sausage.
Add some additional olive oil to the pan, and drop in the hash browns. Add salt and pepper if they aren't already seasoned. Let crisp up for about 7 minutes, flipping over halfway through. Don't let it burn!
Add potatoes to the mixing bowl, and add that small can of green chilies. Sprinkle in some additional salt and pepper, and carefully mix to combine everything. Just a folding method to mix it to try and keep the potatoes from mashing.
In a separate mixing bowl, whisk eggs and milk together with a dash of salt and pepper.
Spray or grease a 13- x 9-inch baking dish. Add potato mixture to the bottom, and smooth out into 1 layer. Add a layer of cheese on top. Now pour the egg mixture over the whole thing, and sprinkle some more cheese on top of that. You'll need somewhere between 1 and 2 cups of cheese, so just do it to your liking. Cover with aluminum foil and let sit in fridge for 5-6 hours.
Preheat oven to 350 degrees and pop in the oven, still covered in foil, for 30 minutes. Remove foil and let cook for another 10-15 minutes. Remove and let cook for a few minutes before serving.