2Mexican chocolate rounds, about 3.15 ounces or 90 grams each, coarsely chopped
Pour the heavy cream and milk in a medium saucepan. Add the vanilla bean, seeds from the vanilla bean and salt; stir and place over medium heat. Stirring constantly, bring to a simmer, about 8 to 10 minutes. Remove from heat immediately after it reaches a simmer, cover and let rest of at least 5 minutes.
Meanwhile, in a medium bowl, using a whisk or fork, beat the egg yolks with the sugar until the mix turns from bright to pale yellow, it thickens and loses its graininess. It will take a couple minutes.
Uncover the milk mixture, remove the vanilla bean, pressing any remaining seeds into the milk. Discard the bean. Slowly, using a ladle, pour half the milk mixture into the yolk mixture, whisking as you go to temper the egg yolks.
Pour the tempered egg yolk mixture into the saucepan with the remaining milk mix. Set over medium heat again, and let it come to a gentle simmer, constantly stirring, until it coats the back of a wooden spoon, about 5 minutes. Remove from the heat and let it cool slightly, stirring now and then.
Using a fine strainer, mesh or cheesecloth, strain the mixture into a metal container. Cover and place in the refrigerator until it is completely chilled, at least a couple hours and preferably up to 12 hours.
Process the ice cream in your ice cream machine according to the manufacturer’s instructions. A couple minutes before it is ready, add the chocolate chunks. Lastly, drizzle in the dulce de leche or cajeta and immediately turn the machine off, so that you create a swirled effect and not a complete mix.