Process pistachios, sugar, oil, vanilla, and salt in a high-speed blender until a smooth, pourable nut butter forms. Stir in the tahini at the end.

Melt butter in a skillet over medium heat. Sauté the shredded kataifi until it achieves a deep, golden-brown crunch. Let cool completely before folding into your pistachio cream.

Temper your chocolate by melting two-thirds over a double boiler, then gradually whisking in the remaining third off-heat until smooth. Brush the interiors of your silicone molds with a thin, even layer of chocolate and chill until set.

Spoon the pistachio-kataifi mixture into the chilled molds, leaving a small gap at the top. Spread a final layer of tempered chocolate over the filling to seal the bars.

Refrigerate until fully hardened, then carefully release from the silicone molds. Store in a cool, dry place.