Meanwhile, in a large saucepan, combine cream, sugar, mascarpone, espresso powder, and vanilla bean and seeds OR omit the vanilla bean step and use vanilla bean paste. Bring the mixture to a low boil over medium heat, whisking until sugar dissolves, about 1 minute. Remove from heat; cover and let stand for 10 minutes.
Remove vanilla bean if you used the bean. Return cream mixture to a low boil. Add gelatin mixture, and stir until dissolved.
Divide cream mixture among 8 (½-cup) ramekins.Refrigerate, uncovered, until mixture is set, at least 6 hours(overnight is better).
Run a thin, sharp knife around the edge of each panna cotta. Invert ramekins onto dessert plates, allowing panna cotta to settle out onto plate. Serve with slightly warm Espresso Caramel Sauce.