In medium pan, whisk together milk and egg yolks. In small bowl, stir together sugar, cornstarch and salt. Whisk sugar mixture into milk mixture. Bring to a simmer over medium heat, stirring constantly with a flexible spatula or wooden spoon, 4 to 6 minutes. When mixture starts to bubble around edges, cook it gently, stirring constantly for 1 minute. Immediately divide the pudding between two heatproof bowls. Stir chocolate into one bowl until it is melted and smooth. Stir the vanilla into the other portion. Let pudding cool to room temperature for about 15 minutes. Spoon the two flavors alternately into ice pop molds, beginning with the chocolate. You can rap the molds firmly on the counter a few times to settle any air pockets. Insert sticks. Freeze until firm, at least y6 hour or up to 1 week. To unmold pops, run hot water over outsides of molds for a few seconds, then gently pull sticks. Makes 6 to 8 pops. For variation, for plain vanilla pudding pops omit the chocolate and increase vanilla to 1 t. skip the step of dividing the mixture in half. For chocolate pudding pops, increase the chocolate to 4 oz. and omit the vanilla.