Toast the kataifi

• Chop the kataifi pastry finely.
• Melt the butter in a frying pan and toast the kataifi until golden and crisp, stirring often.

Make the pistachio filling

• Mix the toasted kataifi with the pistachio paste and the chopped pistachios until a thick, spreadable filling forms.

Melt the chocolate

• Melt the milk chocolate in a bowl over a saucepan of simmering water.
• Melt the white chocolate separately and stir in the pistachio butter.

Build the bar

• Pour half of the milk chocolate into a lined baking dish and spread evenly.
• Chill until set, then spread the pistachio filling over the chocolate layer.
• Cover with the remaining milk chocolate and drizzle with the pistachio white chocolate to marble.

Set and cut

• Chill the bar until completely firm, then cut into pieces.