Preheat oven to 350 degrees. Line the bottom of a springform pan with parchment.
In a large bowl, combine flours, baking powder, salt and zest. Stir well and set aside.
In the bowl of an electric mixer, combine oil and sugar. Beat on medium speed for 2 minutes. Add the eggs, one at a time, mixing for 60 seconds between each addition. Scrape down bowl. Turn mixer to lowest setting and slowly add the flour into the wet ingredients. Stir until just combined.
Pour into prepared pan. Bake for 40-45 minutes, until center is set. Remove cake from oven to cool.
Prepare the topping. Place pistachios into a non-stick skillet over medium low heat. Cook for 5-7 minutes, until toasted. Stirring occasionally. Add the honey and orange juice to the pan. Cook for another 5 minutes. You should see the honey bubble. Remove from heat and immediately top the cake.