Prep the veg: Dice the tomato, onion, and pepper, and slice the mushrooms. Chop the ham into small pieces.
Cook the veg: Spray a frying pan with low-calorie cooking spray and set over medium heat. Add the onions, peppers, and mushrooms, cooking for 3–4 minutes until softened.
Add the spinach, tomato, and ham: Stir them into the pan and cook for another 1–2 minutes until the spinach wilts and the ham warms through.
Add the eggs: In a bowl, whisk together the eggs and egg whites and season with salt and pepper. Pour the mixture directly over the cooked ingredients in the pan, tilting to spread evenly.
Add the cheese: Once the eggs begin to set, sprinkle over the grated cheese.
Fold: Fold the omelette in half and cook for another minute, or until the cheese melts.
Server and Enjoy!