Vanilla-pomegranate parfaits

To prepare compote:
Mix 2 tablespoons sugar with 2 teaspoons cornstarch in a small saucepan. Add pomegranate juice, lemon juice and 3/4 cup pomegranate seeds (save 1/4 cup for garnish) ; stir to combine. Bring to a boil over medium-high heat and cook, stirring, until syrupy, about 5 minutes. Transfer to a small bowl. Refrigerate while you prepare the pudding.

To prepare pudding:
Combine milk in a medium heavy saucepan. Scrape in seeds from vanilla bean (or add vanilla extract). Bring to a simmer over medium heat. Remove from the heat, cover and let steep for 5 minutes.
Meanwhile, whisk egg, egg yolk, 1/3 cup sugar and 1 1/2 tablespoons cornstarch in a medium bowl. Reheat the milk mixture just until steaming. Carefully whisk one-third of the steaming milk into the egg mixture. Pour the egg-milk mixture back into the pan. Cook over medium heat, whisking constantly, until very thick, 2 to 3 minutes. Remove from the heat and whisk in butter.

To prepare parfaits: Divide the pomegranate compote among six 6-ounce (1 cup) parfait glasses, ramekins or other small dessert cups). Spoon the pudding mixture over the compote. Cover and refrigerate until the pudding is well chilled, at least 3 hours.
To serve, garnish each parfait with pomegranate seeds and a mint sprig, if desired.