Preheat your oven to 375°F (190°C) and lightly grease a small oven-safe baking dish with a touch of oil.
Heat the olive oil in a skillet over medium heat; add the ground turkey sausage and cook until browned, breaking it into small crumbles with a spatula.
Add the diced yellow onion and red bell pepper to the skillet, sautéing for 4-5 minutes until the vegetables are tender and slightly caramelized.
Toss in the baby spinach and stir for 1 minute until just wilted, then remove the skillet from the heat.
In a mixing bowl, whisk together the whole eggs, egg whites, sea salt, black pepper, and garlic powder until the mixture is light and frothy.
Transfer the sausage and vegetable mixture into the prepared baking dish, spreading it out into an even layer.
Pour the egg mixture over the sausage and vegetables, ensuring the liquid fills all the gaps.
Bake for 20-25 minutes, or until the eggs are fully set in the center and the top is lightly golden brown.