Preheat the oven to 250 degrees F. Line a large baking sheet with parchment paper. In a bowl, beat together the egg whites, cream of tartar and vanilla until soft peaks form. While still beating, slowly add the sugar until all is incorporated. Keep beating until the mixture is thick and glossy and stiff peaks form. Fold in the dried cranberries. Drop heaping tablespoons of the meringue mixture onto the prepared baking sheet, spacing each cookie about 2" apart. Bake for 20 minutes, or until very light golden. Turn the oven off and let the cookies sit in the oven for another 30 minutes. Cool the cookies on a baking rack. Store cookies, not touching, in an airtight container until ready to serve.