Line a 12-cup muffin pan with paper liners. Melt the dark chocolate with the coconut oil, stirring until completely smooth.
Spoon about 1 tablespoon melted chocolate into each liner and spread it across the bottom and slightly up the sides. Refrigerate the shells for 10 minutes.
Melt the vegan butter in a skillet over medium heat. Add the kataifi and cook for 6 to 8 minutes, stirring frequently, until evenly crisp and golden.
Remove the kataifi from the heat and stir in the pistachio cream, tahini, and fine salt. Cool for 5 minutes, then divide the filling among the chocolate shells.
Cover each cup with the remaining melted chocolate. Gently tap the pan against the counter to level the tops.
Sprinkle with chopped pistachios and flaky sea salt. Refrigerate for 30 minutes, or until firm, then let the cups stand at room temperature for 5 minutes before serving.
