Break chocolate into small pieces. In a food processor pulse together chocolate and butter until chocolate is finely chopped. In a small saucepan whisk together cream, espresso powder, and salt and bring just to a boil. Pour hot cream mixture over chocolate mixture and pulse until smooth. Transfer mixture to a bowl. Let mixture stand at cool room temperature until just firm enough to pipe, about 2 hours.
Oil a large baking sheet and line with parchment paper.
Transfer chocolate mixture to a pastry bag fitted with a 1/2-inch plain tip. Pipe mixture onto baking sheet to form 1-by-1-inch cones. Chill, uncovered, until firm, at least 3 hours, and up to 1 day.
Into a small bowl, sift cocoa powder. Working with 1 smooch at a time, roll in cocoa powder to coat. Smooches keep in an airtight container at cool room temperature or chilled, 2 weeks
Recipe courtesy of Gourmet Magazine