"This is for those of you who tend to break your omelet every time you attempt to make one. With my busted-up veggie omelet, you can have flavor, texture, and no apprehension about keeping the eggs together! I've made this as nutritious as I can without sacrificing flavor."
Heat oil in a medium-sized skillet over medium heat.
Whisk egg whites, egg, and milk together in a small bowl. Toss tomato, onion, mushrooms, and spinach together in a separate bowl.
Pour egg mixture into the hot skillet. Cook until firm on the bottom, about 1 minute. Flip the omelet using a spatula; don't be meticulous, it's supposed to be busted up. Immediately add the tomato mixture and sprinkle mozzarella and Parmesan cheeses on top. Let cheeses melt slightly, about 2 minutes.
Push omelet onto a plate using the spatula. Season with salt and pepper.