Preheat your oven to 350 degrees.
Spray a pie dish with non-stick spray. Place the thawed spinach or (fresh) and spread it out on the bottom of the pie dish. Next add the crumbled feta and green onions.
In a medium bowl whisk together the eggs until fairly smooth. Add the milk, garlic, Parmesan, and sprinkle of pepper. Whisk to combine. Pour this mixture into the pie dish over the spinach, and feta.
Sprinkle the shredded cheese over top. Place the pie dish on a baking sheet for easy transfer into the oven. Place the quiche into the preheated oven and bake until it is golden brown on top and the center is solid. Every oven is different but this should take between 45 minutes and an hour. Slice and serve!