Start by chilling your silicone molds in the refrigerator. Melt the white chocolate with a teaspoon of coconut oil for about 30-45 seconds, stirring until smooth. Use a fork to fling the melted mixture into the molds, creating a decorative splatter. Chill the molds in the freezer for 10 minutes until set.

In a pan over medium heat, melt 4 tablespoons of unsalted butter. Once bubbling, add the shredded kataifi and toast, stirring frequently for 6-8 minutes, until golden and crispy. Remove from heat and allow to cool slightly before mixing with the filling.

In a mixing bowl, combine the toasted kataifi with 200 grams of pistachio paste and ¼ cup of tahini. Mix well until the mixture is smooth and spreadable, resembling a thick cookie dough.

Temper 400 grams of your choice of milk or dark chocolate by finely chopping it, melting two-thirds over a double boiler, and adding the remaining chocolate until fully melted and cooled to about 31-32°C (88-90°F).

Once your chocolate is tempered, brush a thin layer along the sides and bottom of the chilled molds using a pastry brush. Place the molds back in the freezer for 5-10 minutes until hardened.

Carefully spoon the prepared pistachio-kataifi filling into each mold, leaving a little headspace for the final layer of chocolate.

Cover the filling with another layer of tempered chocolate, spreading it evenly to seal the bars. Tap the molds gently on the counter to release trapped air bubbles.

Place the molds in the refrigerator and chill for about 30 minutes, or until the chocolate has completely set. Gently remove the bars from the molds and sprinkle with flaky sea salt if desired.