This traditional Russian dessert can be made with any berries, with currants, even rhubarb.
Cook 3 cups of cranberries in 2 cups of water until very soft. Blend or rub through a sieve. Return puree to the pot, bring to a boil and add 3/4 cup sugar. Reduce heat and stir in one tablespoon potato starch or cornstarch which has been dissolved in one tablespoon of water. Cook stirring constantly until slightly thickened. Pour into dessert dishes or glasses. Sprinkle a bit of sugar over the surface. Serve hot - or chill and top with sour cream or sweetened whipped cream. A cookie would be welcome.