Roll marzipan onto well-powdered workspace 1 cm (approximately 1/3 inch) thick using a rolling pin covered with powdered sugar. Use a small heart-shaped cookie cutter to cut marzipan into many small hearts. Knead remaining marzipan, roll out, and cut with cookie cutter. Repeat process until all marzipan is used.
Melt chocolate in a water bath. Use a fork to immerse each marzipan heart in a chocolate. Drain chocolate-coated marzipan hearts, place on a dish rack or paper and leave to set. Sprinkle candies with pistachios or almonds while still soft then let solidify.