Preheat the oven to 350 degrees. Coat a mini baking dish with cooking spray.
Mix the eggs with the milk until well combined then season with sea salt and freshly cracked pepper, to taste.
Place a sprinkling of oregano, feta cheese, kalamata olives, red onion, spinach, and tomatoes into the mini baking dish; add the egg mixture then top with the remaining ingredients.
Place into the oven and bake for 25-30 minutes, or until a tester inserted into the center comes out clean.
Remove from the oven and serve immediately. Enjoy.