In a small saucepan, bring ½ cup milk, condensed milk, cream, vanilla, and salt to a boil over medium heat. Remove from heat; cover and let stand for 30 minutes.
In a large bowl, place ½ cup milk; sprinkle with gelatin (do not stir); let stand for 10 minutes.
Return warm milk mixture to a low boil over medium-high heat, stirring constantly. Add to gelatin mixture, stirring until gelatin is dissolved. Stir in remaining 1½ cups milk. Strain mixture through a fine-mesh sieve. Reserve 1 cup milk mixture; cover and refrigerate for up to 2 hours. To remaining mixture, whisk in espresso powder and cocoa.
Pour about ½ cup espresso mixture into each of 6 (6- to 8-ounce) glass jars. Refrigerate for 2 hours.
Divide reserved 1 cup milk mixture among jars (about 3½ tablespoons each). Cover with plastic wrap, and refrigerate overnight. Garnish with chocolate shavings, if desired.
Recipe by Taste of the South at https://tasteofthesouthmagazine.com/vietnamese-coffee-panna-cotta/