1. In a mixing bowl, whisk the eggs, milk, salt, and pepper together.
2. Heat the olive oil in a non-stick skillet over medium heat.
3. Add the chopped baby spinach to the skillet and cook until wilted, about 2 minutes.
4. Pour the egg mixture into the skillet over the spinach. Cook until the edges start to set, then gently lift the edges with a spatula to let the uncooked eggs flow underneath.
5. Once the omelet is mostly set, fold it in half and cook for another minute. Serve hot.