- Combine the finely chopped pistachio nuts and caster sugar, and set aside.
- Combine the ground almonds and icing sugar with enough orange-blossom water to form a stiff paste.
- Knead until smooth and allow to rest for about 10 minutes.
- Shape the paste into small balls the size of a walnut, and using a teaspoon handle, make a small hole in each ball and and fill it with the combined pistachio nuts and caster sugar; close the hole over the filling and reshape to a round shape.
- Roll the balls in icing sugar and place in small paper cups or on a serving plate.
- Decorate the top of each ball with a peeled pistachio nut.
- Serve with coffee.