Preheat the oven to 375°F (190°C) and lightly grease a 9x13 inch baking dish with non-stick spray.
In a large mixing bowl, whisk together the eggs, egg whites, and ricotta cheese until the mixture is uniform and the ricotta is broken down into small, creamy curds.
Whisk in the garlic powder, sea salt, and black pepper.
Layer the asparagus pieces, peas, chopped spinach, and spring onions evenly across the bottom of the prepared baking dish.
Pour the egg and ricotta mixture over the vegetables, ensuring even distribution.
Sprinkle the grated Parmesan cheese over the surface of the egg mixture.
Place the dish in the center of the oven and bake for 30 to 35 minutes, or until the center is set and no longer jiggles.
Remove from the oven and allow the dish to rest for 5 minutes before slicing into 6 equal portions.