Grease a round cake pan with cooking spray. In a bowl, whisk eggs, milk, a pinch of salt and black pepper until well combined.
Pour the mixture into the round pan. Top half the mixture with spinach and red peppers. Carefully transfer pan to airfryer basket. Cook for 6-10 minutes at 200 degrees.
Remove the pan. Top vegetables with cheese and, using a spatula, fold the omelet over the filling. Slide omelet into a plate and top with cherry tomatoes.