How to Make It
In a small, heavy saucepan, stir together the granulated sugar and lemon juice. Cook over high heat, washing down the side of the pan occasionally with a wet pastry brush. Reduce the heat to moderate and pour in the heavy cream in a thin stream, stirring; watch out for splatters. Bring to a boil, washing down the sides of the pan; boil over moderately high heat for 3 minutes. Pour into a bowl.
Place the chopped chocolate in a small bowl. Bring the cream to a boil. Pour the hot cream over the chocolate and stir until melted.
Scoop six 1/3-cup balls of coffee ice cream onto a plate lined with plastic wrap and freeze while your proceed.
Preheat the oven to 350°. In a food processor, finely grind the chocolate wafers with the confectioners' sugar; transfer to a bowl. Stir in the melted butter. Spoon 3 tablespoons of the crumbs into the center of six 3-inch fluted tartlet pans. Press the crumbs firmly and evenly on the bottom and up the sides of the pans. The crusts should be about 1/4 inch thick.
Place the crusts on a baking sheet and bake for 10 minutes. Transfer to a rack to cool.
Slip the tartlet shells out of their pans and place on a baking sheet lined with parchment paper. Place an ice cream mound in the center of each tartlet. Freeze.
Spoon about 2 tablespoons of the caramel sauce onto each of 6 warm dessert plates. Dot or swirl the chocolate sauce onto the caramel sauce.
Preheat the oven to 500°. Place the egg whites and superfine sugar in the large bowl of a standing electric mixer and set it over a saucepan of barely simmering water; don't let the bottom of the bowl touch the water. Whisk the whites vigorously until warm. Then beat the egg whites with the mixer at high speed until foamy. without stopping the machine, add the cream of tartar and beat until stiff and glossy, about 5 minutes.
Remove the sheet of tartlets from the freezer. using a metal icing spatula or a pastry bag fitted with a #5 star tip (about 1/2 inch), completely cover the ice cream with meringue, sealing at the rim of the tartlet shells.
Bake the tartlets for about 1 minute, or until the meringues are nicely browned; watch carefully. Immediately place on the prepared dessert plates and serve.