Arrange tart shells on a baking sheet. Fill each shell with about 1 tablespoon each spinach and cheese.
Whisk together eggs and next 3 ingredients. Spoon egg mixture evenly into tart shells. Sprinkle lightly with nutmeg.
Bake at 375° for 30 to 35 minutes or until tarts are puffed and crust is lightly browned. Let stand 5 minutes before removing from foil pans.
Make Ahead: To make ahead, simply fill the pastry with the spinach and cheese, and prepare the egg mixture. Cover both, and chill overnight. Next day, fill tarts with egg mixture, and bake.
Christmas With Southern Living 2006