Clean and dry the chocolate bar molds thoroughly, then set them aside until needed.
Place the white chocolate in the microwave-safe bowl.
Microwave it for 15-30 second intervals, stirring in between until the desired consistency of the melted white chocolate is reached.
Add one teaspoon of the pistachio butter to the melted white chocolate. Stir to combine.
Use a spoon to drizzle the white chocolate throughout the chocolate molds and set in the freezer until needed.
Add the unsalted butter to a skillet over medium heat. Melt the butter, then add the katafi pastry dough to the pan.
Cook for 7-10 minutes until the katafi is crispy and golden brown.
Remove the pan with the toasted katafi from the heat. Add the remaining pistachio nut butter and tahini to the crunchy katafi pastry.
Add the remaining pistachio butter, tahini, and salt to the browned katafi pastry and mix until combined. Allow to cool for 10-15 minutes
Mix until well combined, and let it cool for 10-15 minutes.
Place half of the milk chocolate in a microwave-safe bowl.
Melt in 30-second intervals, stirring between each interval. Heat until the desired consistency of melted chocolate is reached.
Pour the milk chocolate into the chocolate bar mold over the top of the white chocolate. Use a rubber spatula or pastry brush to create an even level, then place it in the freezer for 10-15 minutes.*Don't skip the freezer time, it's essential! Remove the chocolate molds from the freezer. Sprinkle the cooled katafi pistachio mixture evenly into both molds.
Use a rubber spatula to spread the mixture into an even layer, then return the molds to the freezer for 10-15 minutes.
While the filling is setting up in the freezer, melt the remaining milk chocolate in the microwave in 15-30 second intervals until the desired creamy consistency is reached.
Pour the remaining melted chocolate over the top of the katafi. Use a rubber spatula or pastry brush to smooth the remaining chocolate evenly.
Place the chocolate bars in the freezer for 15 minutes or in the refrigerator for 30 minutes. Then pop them out of the molds.
*This recipe yields two large chocolate bars, which can be broken into 10 pieces each. For fun, bite-sized treats, try using peanut butter cup molds.