Preheat your oven to 350 °F (175 °C).

Transfer the sugar, flour, cocoa powder, baking powder, cinnamon, and salt to a large bowl and mix with a whisk.

Add the oil, milk, vanilla, and egg and whisk until smooth.

Pour the batter into a greased, floured, and parchment-lined 8-inch round cake pan. Bake for 37-40 minutes or until a toothpick comes out clean.

Chop the kataifi pastry and fluff it up with your hands.

In a pot over medium heat, add butter and kataifi pastry. Stir constantly until deep golden brown. Transfer to a bowl to cool.

Melt the white chocolate (and vegetable oil if using), then mix in pistachio butter and salt. Let cool until slightly thickened.

Add toasted kataifi to the pistachio cream and mix well.

Whip the cold heavy cream until soft peaks form, add honey, then melted dark chocolate and mix until homogenized. Refrigerate.

Take the ganache out of the fridge to warm slightly. Trim the dome off the cake and slice it in half.

Transfer one layer onto a cake platter. Pipe a border with ganache and fill with pistachio filling.

Cover with the second layer and frost the cake with remaining ganache.

Smooth the surface with a hot offset spatula and sprinkle chopped pistachios on top.