The cake can be kept covered at room temperature overnight. The rhubarb jam and mascarpone cream can be refrigerated overnight. Bring the rhubarb jam to room temperature before serving.
Moscato d'Asti, a lightly sparkling, lightly sweet wine from Italy's Piedmont region, has a fresh, tangerine-scented liveliness that makes it a terrific partner for not-too-sweet dessertsCorry's polenta cake is a case in point. Ideally, Moscato d'Asti should be drunk the same year it's released; aging merely dulls its youthful vivaciousness.