In a small saucepan, bring 1 cup water to a boil. Add oats and pinch of salt; stir, reduce heat, and simmer until tender, about 5 minutes. Meanwhile, heat a small nonstick pan over medium. Coat lightly with cooking spray. Add egg and cook until white is set and yolk is still runny, about 3 minutes. Season egg to taste with salt and pepper. Serve oatmeal in a bowl topped with cheese, egg, and scallion greens.