Melt your colored or white melting candy according to package instructions and drizzle it into your clean dry candy bar mold. Drizzle it in a random pattern or make a design it's up to you, this will be the top of your candy bar. Place the mold in your refrigerator for about 15 minutes to harden. When removing the mold from the refrigerator make sure not to bend the mold if it's silicone, you’ll pop the design out or crumble it.
Melt 1 cup of melting chocolate according to package instructions and spread it over the bottom and sides of your chocolate bar mold. You can use a pastry brush or just tilt the mold so the chocolate covers all sides. Turn the mold over so the excess chocolate can run out. Use a flat knife or scraper to get the extra chocolate off the sides of the mold. Place
the mold back in the refrigerator to set for at least 15 minutes.
While the chocolate sets, toast your kataifi. In a non-stick skillet, coat your kataifi in the butter and heat over medium heat until toasted, do not overheat or it will burn. Set it aside for a few minutes to cool.
In a medium bowl, combine the pistachio butter with the tahini. Once combined add the toasted kataifi and fold it in until well mixed.
Spread this mixture over the chocolate in your mold leaving a tiny space around the outside so chocolate can wrap around the filling on the sides.
Heat the remaining cup of chocolate and spread it over the filling making sure to fill the entire mold. Use a flat knife or scraping tool to remove any excess chocolate and make the bottom of your chocolate bar flat.
Refrigerate the candy bar for about 30 minutes or until set.
Pop the chocolate out of the mold carefully and enjoy.