1 Scrape and deburr the mussels, wash them. Place them in a casserole and cook them for about 8 minutes, until they are open. Drain them, reserve 25 cl of cooking juices and shell the mussels.
2 In a saucepan, reduce the cooking juices of the mussels until they are softened to the equivalent of 4 tablespoons. Reserve
3 Peel the garlic, mix it with the hazelnuts, the basil leaves and the reduced juice of the mussels. Pour the oil on the top while mixing. Salt little (or not) and pepper.
4 In a saucepan, mix the mussels with the hazelnut pesto and stir 1 to 2 minutes over low heat. Serve hot, with fresh tagliatelle for example.