Finely grind the pistachios. Grate the marzipan finely and knead well with the pistachios and maraschino liqueur.
Fill the dates with the paste and gently press together.
Coarsely chop the dark chocolate and melt over a pan of hot water. Dip the dates into the chocolate, drain and leave to dry on a wire rack.
Keep the dates chilled and serve in paper sleeves.