Preheat oven to 350 degrees F (175 degrees C). Grease a 13 x 9 inch baking dish with cooking spray.
In a medium skillet over medium heat, crumble and brown bulk sausage until fully cooked. Drain.
Place the hash brown potatoes in the bottom of the baking dish evenly, pressing down gently. Top with half of the shredded cheese.
Top with Rotel , sausage and green onion. (Set aside 2 tablespoons green onion for garnish, if desired.)
Bake in the preheated oven for 50 minutes to 1 hour, or until egg is fully set.
Remove cover and top with remaining cheese.