Prepare a wire rack or a sheet of parchment on a rimmed baking sheet and set aside.

In a small bowl, whisk the egg white until lightly frothy. In a separate medium bowl whisk together the sugar and cinnamon (if using.) Add the cranberries to the bowl with the egg whites and toss to coat. Move the cranberries to the bowl with the sugar and gently toss. Transfer to the rack or parchment and leave to dry uncovered at room temperature for two hours. Use as garnish or eat on their own!