Place an oven rack in the centre of the oven and preheat to 190 C / Gas 5. Grease a 12-hole muffin tin.
In the bowl of a food processor, pulse together the apricots, walnuts, honey, orange zest, orange juice and cardamom, until the apricots are in about 5mm pieces.
Place a sheet of filo pastry on a work surface. Brush the pastry with melted butter. Place another sheet of pastry on top and brush with melted butter. Repeat with remaining pastry and melted butter. Using a sharp knife, trim the pastry into a 30x23cm rectangle. Cut the dough into 12 square pieces. Gently press each piece of pastry into the muffin pan.
Spoon the apricot filling into the cups. Bake until golden about 12 to 14 minutes. Remove from the oven and let the filo cups cool for 10 minutes. Using a dessert spoon or a small spatula, remove the filo cups from the pan. Place on a rack and cool completely.
Arrange the filo cups on a platter, garnish with orange zest, if using, and serve. Or, store in an airtight plastic container for up to 4 days.