Preheat your oven to 400°F. Grease a 9×9-inch round baking dish with olive oil, ensuring the sides are well-coated to prevent sticking.
In a large bowl, whisk together the egg whites, cherry tomatoes, red onion, baby spinach, salt, pepper, blended cottage cheese, minced garlic, and Italian seasoning until well combined.
Pour the egg white mixture into the greased baking dish. Place the dish on a baking sheet lined with parchment paper to catch any drips and make cleanup easier.
Bake in the preheated oven for 30 minutes or until the egg whites are set and the top is lightly golden. Let the frittata cool before slicing into portions.