1. Combine 1 cup granulated sugar and 1 cup water in a small heavy saucepan over medium-high heat, stirring until sugar dissolves. Bring to a simmer; remove from heat. Combine the sugar syrup and cranberries in a small bowl. Cover and chill for 4 hours.
2. Drain cranberries in a colander over a bowl, reserving liquid for another use, if desired. Place sparkling sugar in a shallow dish. Add cranberries, rolling to coat. Spread sugared cranberries in a single layer on a baking sheet; let stand at room temperature 1 hour or until dry.
3. Combine remaining 1/3 cup granulated sugar, cornstarch, and salt in a large bowl, stirring well. Combine 1/2 cup milk and egg yolks in a small bowl, stirring with a whisk. Heat remaining 2 cups milk in a medium heavy saucepan to 180° or until tiny bubbles form around edge (do not boil). Stir egg yolk mixture into cornstarch mixture. Gradually add half of hot milk to sugar mixture, stirring constantly with a whisk. Add egg yolk mixture to pan; bring to a boil. Cook 1 minute, stirring constantly with a whisk. Remove from heat. Add vanilla and chocolate, stirring until chocolate melts. Spoon pudding into a bowl; place bowl in a large ice-filled bowl for 15 minutes or until pudding cools, stirring occasionally. Cover surface of pudding with plastic wrap; chill 20 minutes.
4. Combine whipped topping and mascarpone in a bowl, stirring until well blended. Spoon about 1/3 cup pudding into each of 8 bowls or footed glasses; top each serving with about 3 tablespoons mascarpone mixture and about 2 tablespoons cranberries.