Day 1 – Prepare Components:
Preheat oven to 350°F (175°C). Grease and line two 8-inch round cake pans.
In a large bowl, whisk together flour, cocoa powder, sugar, baking powder, cinnamon, and salt.
In a separate bowl, whisk eggs, olive oil, milk, and vanilla until smooth.
Combine wet and dry ingredients, mixing just until combined. Divide batter between pans and bake for 25–30 minutes, or until a toothpick inserted comes out clean. Cool completely.
Toast kataifi: Gently separate strands and toast in a large skillet with butter over medium heat until golden and crisp. Set aside to cool.
Make pistachio filling: Melt white chocolate and allow to cool slightly. Stir in pistachio butter and optional oil. Fold in toasted kataifi. Chill until set.
Make whipped ganache: Heat cream and honey until steaming. Pour over chopped chocolate and let sit for 5 minutes. Stir until smooth, then cool to room temperature. Refrigerate until slightly firm, then whip until light and fluffy.
Day 2 – Assemble:
Level cake layers. Place one on serving plate. Pipe ganache around the edge to form a border.
Fill center with pistachio-kataifi mixture. Top with second cake layer.
Frost entire cake with whipped ganache. Chill at least 2 hours before serving.