Place chopped dark chocolate in a heatproof bowl.

In a small saucepan, heat heavy cream, butter, caramel sauce, and espresso powder over medium heat until just simmering.

Pour the hot mixture over the chocolate, letting it sit for 2 minutes before stirring until smooth.

Stir in vanilla extract and salt.

Cover and refrigerate for 2–3 hours, or until firm enough to scoop.

Scoop small portions and roll into balls. Place on a parchment-lined baking sheet and chill for 30 minutes.

Melt the coating chocolate in a heatproof bowl over simmering water or in short microwave bursts.

Dip each truffle in the melted chocolate, shaking off excess, then return to the tray.

Garnish with cocoa powder or sea salt flakes, if desired, and let set at room temperature or in the fridge.