Place the unsalted butter in a large saucepan and melt over low heat.

Tear the filo pastry into small pieces and place in the saucepan.

Over medium heat, move the filo around until crunchy, golden, and toasted, which can take at least 5 minutes. Remove from heat and transfer to a bowl.

Microwave the pistachio cream for 10-20 seconds, stir until melted and smooth.

Pour the pistachio cream over the toasted filo (saving 2 tablespoons for decoration) and stir until fully coated. Set aside to cool.

Chop the unsalted butter into chunks and place in a large mixing bowl. Beat until soft but not creamed.

Mix in the light brown sugar and white caster sugar until combined.

Add the eggs to the mixture and stir until just combined.

In a separate bowl, whisk the self-raising flour, plain flour, cocoa powder, and salt together until combined. Add this mixture to the butter mixture and fold to create a thick cookie dough.

Fold in the milk chocolate chips.

Line a baking tray with greaseproof paper. Break off large heaped tablespoons of cookie dough, flatten in your palm, add a teaspoon of pistachio filling in the middle, and wrap the dough around it to form a ball. Repeat until all dough is used.

Place the rolled cookies on the baking tray and wrap the tin tightly in foil. Freeze for 90 minutes.

Preheat the oven to 200?C fan / 220?C conventional. Line another baking tray with greaseproof paper and place in the oven for 5 minutes to heat up.

Place 4-5 frozen cookies on the preheated tray, leaving space between each. Bake for 12-15 minutes until firm on the edge but soft in the middle. Leave to cool on the baking tray for 15 minutes.

Microwave the saved pistachio cream for 10-20 seconds, stir until melted and smooth. Pipe or drizzle onto the cookies.