Preheat oven to 450°F. Cook spinach according to package directions. Drain well and reserve. Coat medium skillet with cooking spray. Using medium heat, sauté onions until soft. Add spinach to pan and mix thoroughly. Season to taste with salt, pepper, and nutmeg. Add Marsala wine. Raise heat and boil for 1 minute. Remove from heat, and allow to cool slightly. In a medium bowl, beat together egg substitute and cream. Spray quiche dish with cooking spray. Spread cheese to cover bottom of quiche dish. Pour in egg mixture and gently mix. Add spinach mixture to egg and cheese mixture. Bake for 15 minutes. Reduce heat to 375°F and bake for another 20 to 25 minutes or until quiche is brown and firm and a utensil inserted into center comes out clean.