Preheat oven to 375° F. Lightly coat an 8-inch pie pan with non-stick cooking spray.
In a 3-quart saucepan cook the mushrooms and spinach until wilted, about 4 to 5 minutes. Drain mushrooms in a colander, and squeeze spinach to remove excess moisture. Chop spinach lightly, and set mushrooms and spinach aside.
In a medium-sized bowl whisk together the eggs and defrosted egg replacement, then stir in the grated cheese, milk, tarragon, pepper and salt. Add the mushrooms and spinach, and mix well.
Pour the egg-vegetable mixture into the pie pan, and bake for 30 minutes on middle oven shelf. Let cool for 10 minutes to set before cutting. Cut into 16 wedges.Servings: 16