Thaw one roll of fillo dough, following thawing instructions on package.
Preheat oven to 350ºF.
Unroll and cover the fillo pastry sheets with a damp towel or plastic wrap to prevent drying out.
Lightly coat tartlet pan with cooking spray.
Place one sheet of fillo on a cutting board and lightly coat with cooking spray. Layer and repeat with 4 more sheets. (Recipe or personal preference may substitute brushing with melted butter, olive oil or egg wash.) If phyllo shells are for a dessert item, lightly sprinkle each layer with sugar after spraying. Finely chopped or ground nuts between sprayed and sugared fillo layers add wonderful flavor.
A general guide is to cut the fillo about 1″ larger than the tart pan, so that the fillo circle is large enough to go completely up the sides of the pan. For 2½” tarts pan, cut 4″ circles and; for 4″ tarts pan, cut 5″ circles.
Place layered circles in the sprayed pan. Carefully push fillo into the pan, pressing firmly against the bottom and sides.
Reroll unused fillo sheets and follow storing instructions on package.
Bake empty shells about 8-10 minutes or until fillo is golden brown. Cool 5 minutes. Remove and fill phyllo shells with your favorite ingredients.