Dark-Chocolate Pudding with Candied Ginger

In a medium bowl, sift together the sugar, cocoa powder, cornstarch and salt. In a large saucepan, add the half-and-half and whisk in the cocoa-powder mixture. Cook over moderate heat, whisking, until the pudding starts to bubble and thicken, about 4 minutes. Remove from the heat and stir in the bittersweet chocolate and vanilla. Pour the pudding into 6-ounce ramekins and let cool, then cover and refrigerate until chilled, about 1 hour. Top each pudding with whipped cream and candied ginger and serve.