For the brownies: Preheat the oven to 350°F and line an 8x8-inch pan with parchment paper, leaving an overhang on the sides. Lightly spray the parchment and set aside. In a microwave-safe bowl, combine the butter and 2 tablespoons chocolate chips. Melt in 30-second increments, stirring each time, until smooth. Stir in the granulated and brown sugar. Mix in the eggs one at a time, mixing well after each, then stir in the vanilla. Add the salt and cocoa powder and stir until almost incorporated, then sift in the flour and fold together — do not overmix. Gently fold in the 1/3 cup chocolate chips. Spread evenly into the pan and bake 23 to 25 minutes, until no longer jiggly in the middle and just set. Don't overbake. Cool on a wire rack slightly. For the pistachio/kataifi layer: While the brownies bake, melt the butter in a large skillet over medium heat. Add the kataifi and cook, stirring often, until golden brown and crispy (about 10 minutes). Set aside to cool. In a bowl, mix the pistachio cream, tahini, and salt until smooth, then stir in the toasted, cooled kataifi. Spread evenly over the slightly cooled brownies. For the chocolate layer: Melt the butter and 1 cup chocolate chips together until smooth (stovetop over medium, or microwave in 20-second bursts). Pour over the pistachio/kataifi layer and spread evenly. Drizzle pistachio cream over the top using a squeeze bottle or a storage bag with a corner cut; if too thick, warm it 10 to 14 seconds first. Chill in the fridge at least 1 hour, until the chocolate is firm (up to 4 hours or overnight). Slice into squares, using a large sharp knife and wiping the blade between cuts for clean slices.