Spinach Frittata
["1 c. flour", "1 tsp. salt", "1 tsp. baking soda", "1/2 stick margarine, melted", "2 eggs, beaten", "1/2 onion, chopped", "1 c. milk", "1/2 lb. Monterrey Jack cheese, grated", "1/2 lb. cheddar cheese, grated", "10 to 16 oz. spinach, chopped and cooked"]
["Mix ingredients in order given and pour into baking dish. Bake at 325\u00b0 for 20 to 25 minutes.", "To make individual servings, bake in muffin pans."]
["flour", "salt", "baking soda", "margarine", "eggs", "onion", "milk", "cheese", "cheddar cheese", "spinach"]