Preheat your oven to 375°F (190°C) and lightly grease a small oven-safe baking dish or cast-iron skillet.
Place the cherry tomatoes in the baking dish, drizzle with olive oil, and roast for 10 minutes until they begin to soften and burst.
While the tomatoes roast, finely mince the garlic and roughly chop the fresh spinach.
In a medium mixing bowl, whisk together the whole eggs, liquid egg whites, and non-fat Greek yogurt until the mixture is smooth and well-combined.
Stir the sea salt, black pepper, and dried oregano into the egg mixture.
Remove the baking dish from the oven, add the garlic and spinach, and stir briefly so the heat of the tomatoes wilts the greens.
Pour the egg mixture over the vegetables in the dish and sprinkle the crumbled feta cheese evenly across the top.
Return the dish to the oven and bake for 15 to 20 minutes, or until the eggs are set in the center and slightly golden on the edges.
Let the dish rest for 2 minutes before serving to allow the flavors to meld.