How to Make It
Preheat the oven to 400°. Put the hazelnuts in a pie plate and toast in the oven for about 8 minutes, or until fragrant. Turn the oven down to 200°. Transfer the hot hazelnuts to a kitchen towel and rub them together to remove the skins. Let the nuts cool.
In a food processor, pulse the hazelnuts with the 1/4 cup of confectioners' sugar just until finely ground.
In a large bowl, using an electric mixer, beat the egg whites with the cream of tartar and salt at low speed until frothy. Add 2 tablespoons of the super- fine sugar and increase the speed to medium. Add another 2 tablespoons of superfine sugar and beat for 30 seconds. Increase the speed to high and slowly beat in the remaining 1/4 cup of superfine sugar. Beat for about 5 minutes, until the meringue is stiff and glossy. Fold in the hazelnuts.
Spoon a heaping tablespoon of the meringue onto a parchment paper-lined baking sheet and spread into a 2 1/2-inch round; repeat to form 48 rounds. Bake for 20 minutes. Turn off the oven and leave the meringues in to dry for at least 3 hours or overnight.
For each ice cream sandwich, scoop 1/4 cup of the ice cream onto the underside of a meringue and top with another meringue. Serve at once or wrap individually in plastic and freeze.