Smooth and creamy, this chilled dessert can be made ahead and served when you need it.
In a small bowl, sprinkle the gelatin over the cold water.
In a saucepan, whisk the cream and milk to heat up. When it is hot to the touch, stir in the espresso powder, sugar, and salt until dissolved.
Pour the hot milk mixture over the chopped chocolate in large bowl and stir until dissolved and incorporated. Whisk one cup of the hot milk mixture into the dissolved gelatin to combine and melt the gelatin. Return the gelatin mixture to the chocolate milk and whisk to fully combine.
Pour into 8 8-ounce-size ramekins, filling halfway. Chill for 3 hours or up to overnight. To serve, dip the ramekin into hot water for a few seconds and run a small knife around the edges to release the custard. Turn out onto a plate and garnish with chopped chocolate.