Grease a 9" x 13" pan and line with croutons. Cook sausage until done. Add mushrooms, green chilies, and onions. Saute. In a bowl, whisk soup, eggs, and milk. Layer sausage mixture over croutons. Pour egg mixture on top. Top with cheese. Cover with foil and refrigerate over night. That's the secret! It has to set over night! Cook at 350 for 1 1/2 hours. Serve hot. A good side; picante sauce.