In a large mixing bowl, combine eggs, milk, salt and pepper. Whisk until smooth; set aside.
Heat olive oil in a medium skillet. Add spinach and onions and saute until onions are tender.
Spray a 10 inch deep dish pie plate with cooking spray.
Layer cooked pasta, sautéed spinach and onions, sun dried tomatoes, and crumbled feta in pie plate.
Pour egg mixture over the top.
Bake at 350 degrees for 45 minutes or until center of frittata is set.