Spray a 9 X 13 pan with nonstick cooking spray and set aside
In a large skillet, cook the sausage and onions until the meat is brown and the onions are cooked. Add the chili powder stir to combine, and remove from heat.
Layer 1/2 cup of the green chile (or 505 if using) sprinkle on 1/3 cup of the sausage mixture and cover with 1/2 of the cut corn tortilla pieces. Sprinkle 1 cup of cheese over top.
Repeat step 3 then finished casserole with the last third of the sausage and 1/2 cup of green chile. Top with 1 cup of cheese.
Beat eggs, milk, salt and pepper in a large bowl. Gently pour over casserole evenly covering the entire dish.
Cover and refrigerate overnight or at least for 6 hours. Before baking remove from fridge and let come to room temperature about 1 hour.
Bake in 350 degree preheated oven for 80 minutes. Cover with foil the last 30 minutes to prevent the casserole from becoming over browned.
Remove from oven and let stand for 10 minutes before slicing.