Preheat oven to 400°F and grease a 10" pie pan and set aside. Steam 6 oz of spinach. Chop ½ an onion and 1 tomato. Then in a medium bowl combine 1 1/3 of milk, 3 eggs, ¾ cup of Bisquick, salt and pepper. Set aside. Combine the spinach, onion, tomato and Feta and place in the bottom of the pie pan. Pour the Bisquick, milk and egg mixture over the top. Bake at 400°F for 25-35 minutes, until puffed and set.