Preheat oven to 350°F. Butter one deep 9-inch cake pan or springform pan (at least 2 ½ inches deep). Line the bottom with a parchment paper round and the sides with a long parchment paper strip. Set aside.
In the bowl of a food processor fitted with a blade attachment, pulse pistachios, orange zest, salt and ¼ cup of flour until finely ground but not a paste. Transfer to a large bowl and mix with remaining 1 ¾ cups flour, baking powder, and baking soda.
In a separate mixing bowl, whisk together buttermilk and vegetable oil.
Place butter in the bowl of a stand mixer fitted with a paddle attachment. Mix on medium speed, scraping down bowl as needed, until smooth. Add sugar; cream mixture until pale and fluffy, about 5 minutes. Mix in egg, yolks and vanilla and beat on medium speed for another 5 minutes, until very light, thick and fluffy.
Reduce speed to low and add the flour mixture to the batter in three parts alternately with the buttermilk mixture, starting and ending with the flour. Mix until just combined.
Divide batter evenly into the prepared pan and smooth the top. Bake until a toothpick inserted in the center comes out clean, 45-50 minutes. Let cool 5 minutes, then run a knife around the edges and carefully turn them onto a cooling rack. Cool completely.
Place cooled cake onto a cake stand or platter and spread with Chocolate Snack Spread (or Vanilla Fudge, if desired). Use the back of a spoon to create swirls on the surface and spoon raspberry preserves on top.
Garnish with fresh raspberries, chocolate curls and chopped pistachios.