Preheat oven to 200F. Cover large baking sheet with parchment paper.
Beat egg whites and cream of tartar in large bowl with electric mixer on medium speed 5 minutes or until soft peaks form. Gradually add granulated sugar, beating on high speed until well blended.
Add powdered sugar, 1 Tbsp. at a time, beating well after each addition. (Meringue will begin to turn glossy.) Continue beating until stiff peaks form. Stir in cranberries and chocolate.
Spread onto prepared baking sheet to within 1/2 inch of edges of baking sheet.
Bake 2 hours. Turn oven off.
Let meringue stand in oven for 2 to 2-1/2 hours or until meringue is cooled and completely dried.
