9 ounces fine-quality bittersweet chocolate (not unsweetened)
3/4 stick (6 tablespoons) unsalted butter, softened
1/2 cup heavy cream
4 teaspoons instant espresso powder*
1/4 teaspoon salt
1 cup unsweetened cocoa powder
*available at many supermarkets
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, or "kisses." Chill kisses, uncovered, until firm, at least 3 hours, and up to 1 day. Into a small bowl sift cocoa powder. Working with 1 kiss at a time, roll in cocoa powder to coat. Kisses keep, in one layer in an airtight container at cool room temperature or chilled, 2 weeks.