Preheat the oven to 350°. Line 2 baking sheets with parchment paper.
Spread the hazelnuts in a pie plate and toast in the oven until fragrant and the skins have blistered, about 12 minutes. Let cool slightly. Wrap the nuts in a towel and rub them together to loosen the skins; let cool completely.
In a food processor, coarsely grind the hazelnuts with the confectioners’ sugar and flour. In a large bowl, using an electric mixer, beat the egg whites at high speed until firm peaks form. Gradually add the granulated sugar and beat until the whites are glossy, about 3 minutes longer. Using a large rubber spatula, fold in the hazelnut mixture until it is fully incorporated.
Transfer the meringue to a large pastry bag fitted with a 1/2-inch round tip. Pipe 1 1/2-inch mounds 1 inch apart on the prepared baking sheets. Bake the meringues on the upper and lower racks of the oven for about 15 minutes, or until the cookies are golden and crisp but still a bit soft inside; shift the pans from top to bottom and front to back halfway through baking. Let the meringues cool on the sheets.
Meanwhile, put the chocolate in a bowl. In a small saucepan, bring the cream to a boil. Pour the cream over the chocolate and let stand for 1 minute, then stir until smooth. Drizzle the chocolate glaze over the meringues and let stand until completely set.