Pre heat oven to 425. Coat a 9-inch pie plate with cooking spray or olive oil.
In a medium bowl beat together eggs, eggwhites, milk, and salt and pepper. Set aside.
Heat oil in a large non-stick skillet over a medium-high heat. Add onion and cook for a few minutes or until they are translucent (about 5 minutes). Stir in garlic and spinach and cook for another couple of minutes.
Transfer veggie mixture to a large bowl and stir in rice and Feta cheese and egg mixture. Pour the egg mixture over the veggies and then transfer everything into the pie pan. Smooth out the top using a spatula.
Bake the pie for about 25 minutes or until lightly browned. Cool for a few minutes before cutting up. Enjoy!