Preheat oven to 375F
In a large bowl combine eggs, salt, pepper and oregano. Whisk until well combined.
In a separate bowl mix spinach, tomatoes and mozzarella.
Grease 12 muffin tins with cooking oil spray.
Fill each muffin tin with the veggie mixture about 1/2 full.
Add the egg mixture to each muffin tin until it is about 3/4 full.
Bake eggs in the preheated oven for about 15-20 minutes.
Store leftovers in the refrigerator and enjoy for 4-5 days.