Bring the 5 cups of water to a boil in a 4-quart saucepan. Whisking constantly, add the polenta in a thin stream until all is incorporated. Stir with a wooden spoon until as thick and dense as cream of wheat. Portion polenta into 4 warmed serving bowls and top each with 1/4 cup of mascarpone.
Recipe copyright 2001, Mario Batali. All Rights Reserved.