Heat oven to 350°. Combine hazelnuts and liqueur in a medium bowl and let sit for 10 minutes. Add sugar and toss to coat; spread nuts in a single layer on a parchment paper–lined baking sheet and bake, stirring occasionally, until toasted, about 10 minutes. Remove from oven and let cool; add apricots and set aside.
Combine chocolate and shortening in a heat-proof bowl and set over a pot of simmering water. Heat, stirring often, until chocolate melts and mixture is smooth. Remove bowl from pot and let chocolate mixture cool until an instant-read thermometer reads to 89°. Working in four batches, combine 1⁄4 of the reserved nut mixture and 1⁄4 of the melted chocolate in a small bowl until nut mixture is coated with chocolate; there should be only enough chocolate to keep the mixture together. Using a tablespoon-size measuring spoon, spoon mixture into mounds on a parchment paper–lined baking sheet; repeat with remaining nut mixture and chocolate. (If chocolate mixture drops below 86°, heat it again, stirring constantly, until it returns to 89°, and then continue mixing with nut mixture.) Let rochers cool and set before serving.