1. Preheat oven to 350 degrees F. Butter a 9-inch round cake pan with removable bottom and line the bottom with parchment paper.

2. Sift pistachio flour, almond flour, cornstarch, and salt together into a mixing bowl.

3. Rub finely grated orange zest into granulated sugar with your fingers until fragrant and evenly distributed.

4. Beat eggs in stand mixer until frothy, then add orange sugar mixture. Increase speed to high and whip for 7 to 10 minutes until very pale and thick.

5. Microwave cubed butter at 50% power in 10-second bursts, stirring between each interval, until just softened but not fully melted.

6. Stir olive oil into the softened butter until combined.

7. With mixer running on low, gradually pour butter mixture into eggs, letting it incorporate fully before adding more. Add pistachio extract.

8. Add sifted flour mixture and mix on low for just a few seconds until no dry streaks remain.

9. Pour batter into prepared pan and bake for 40 to 45 minutes until a toothpick inserted in center comes out clean.

10. Let cake cool completely on wire rack, then remove from pan.

11. Heat heavy cream until steaming, then pour over chopped chocolate. Let sit 30 seconds, then stir from center outward until smooth.

12. Wrap cooled cake with acetate strips secured with tape. Pour ganache over top and let set at room temperature for 1 hour.

13. Sprinkle slivered pistachios around edge before ganache fully sets. Refrigerate until ready to serve.