In a large skillet, over medium heat, cook hash brown potatoes according to package directions. Add fresh spinach to skillet towards the end of cooking time and toss lightly. Cook until spinach is slightly wilted and soft.
In a non-stick skillet, over medium heat, scramble egg whites, seasoning with salt and pepper to taste.
To serve, lay tortillas on a work surface. Fill each with approximately 2 oz. of mozzarella, then spoon in egg whites and potato/spinach mixture, dividing evenly between each tortilla. Roll burrito style, heat in microwave for 30 seconds each, or for a crispier outside, bake in 350 degrees F oven for 5 minutes and serve.