In a mixing bowl, combine the pistachio cream with the toasted kataifi until well blended. Scoop the mixture into tablespoon-sized portions and shape them into balls. Place these filling balls on a parchment-lined tray and freeze for at least 30 minutes until firm.

Preheat your oven to 350°F (175°C) and line baking sheets with parchment paper. Melt the cooled butter in a medium saucepan, then mix in the cocoa powder and avocado oil until smooth. Allow to cool slightly, then stir in granulated sugar, brown sugar, eggs, and vanilla extract until glossy.

In a separate bowl, whisk together cake flour, baking soda, baking powder, and salt. Gradually fold the dry mixture into the wet ingredients until just incorporated without overmixing.

Scoop about 2½ tablespoons of the cookie dough and create an indent in the center. Place one of the frozen pistachio filling balls into the indent and seal the dough around the filling. Space assembled cookies on baking sheets.

Bake for about 10 minutes until puffed up slightly. If needed, flatten them halfway through baking. Edges should look set, and centers remain soft.

Once cooled, melt semisweet chocolate and drizzle over cookies. Sprinkle with chopped pistachios and allow chocolate to set before serving.