Mix the soft butter with the eggs in a bowl until frothy. Mix in the hazelnuts and breadcrumbs. Season with lemon juice, nutmeg and salt. Let the mass swell for 10 minutes. Bring the meat stock to a boil in a saucepan. Cut off the dumplings with 2 teaspoons and cook in the broth over low heat for about 6 minutes. Before serving, sprinkle the stock with chives.