3 Granny Smith apples (or other firm, tart variety)

Powdered sugar

Preheat oven to 250 degrees.  Trim tops off apples and cut in half right down through the core.  Pick out and discard seeds.  With a sharp knife (or mandolin slicer) slice apple into very thin pieces.

Line two baking sheets with parchment paper.  Arrange apple slices in single layer.  Sprinkle with powder sugar.  Bake about  3 hours, or until lightly browned (they'll get crispy as they cool).  Allow to cool completely before storing at room temperature in loosly covered container (so they don't get soft).  Suggestion:  You can also sprinkle ground cinnamon on top before baking.