My daughters spent years in competitive dance. We travelled often and found it best to stay in hotel rooms with kitchenettes so I could feed them properly. I would make this recipe ahead, in foil pie plates, cook it, freeze it, and heat it through in my toaster oven. The girls loved it on pasta, or rice, or even on a toasted bun. Today, I make it in a 9 by 13 inch pan, as a side dish for a roast beef or turkey dinner. I usually use turkey bacon, but, in this instance, I used chipped ham.
First sauté the mushrooms in butter until golden. Remove the mushrooms from the pan and sauté the sliced onions. Brown the bacon or ham. I usually use turkey bacon.
Squeeze excess moisture from the thawed spinach. Arrange the spinach evenly in the bottom of two well buttered pie plates or one 9" by 13" cake pan.
Arrange the mushrooms over the spinach, followed by the onions. Sprinkle with the bacon.
Sprinkle cheddar cheese over top.
Bake the Spinach Pie at 350 degrees F for 20 to 30 minutes, and serve. If you plan to freeze it, just bake it for 10 to 15 minutes, cool and freeze. Place frozen spinach pie in a 350 degree oven for about 40 minutes and you have a great side dish for any meal.