Stir in uncooked pasta and submerge under liquid. Cover and bring the mixture to a boil. Once boiling, reduce heat to low and simmer for 10 minutes, or until the pasta is tender, stirring occasionally.
Stir in spinach, 1 cup at a time, until wilted. Maintain heat so that liquid will continue to simmer and thicken. Season with salt and pepper.
Sprinkle with shredded cheese, cover and let rest for a few minutes, or until cheese is melted. Sprinkle with green onions and serve hot.