Add Greek yogurt to a large measuring cup or mixing bowl with a spout. Set aside.
In a saucepan, combine milk, sugar, gelatin, espresso powder, vanilla, and salt. Stir well before heating.
Heat the mixture over medium heat until it reaches a gentle simmer. Stir continuously to fully dissolve the gelatin and sugar. Do not boil aggressively.
Remove from heat and let cool for 2 to 3 minutes.
Slowly pour the warm coffee mixture into the Greek yogurt while whisking continuously until smooth and fully incorporated.
Divide evenly into four serving glasses or jars.
Refrigerate for 3 to 4 hours until completely set.
Serve as is or top with cacao powder or shaved chocolate.
