Preheat the oven to 375°F. Lightly grease a 9" or 10" springform pan.
To make the crust: Place 1/2 cup of the flour, all the sugar, and the pistachios in the bowl of your food processor. Grind until the nuts are very fine. Transfer the mixture to a large mixing bowl and add the salt, the rest of the flour, and the softened butter. Mix with a paddle until the mixture looks crumbly, then beat in the orange zest and egg.
Press the dough evenly across the bottom and 1" up the sides of the prepared pan. Chill the dough for 10 minutes, then prick it all over with a fork and bake for 20 minutes, until golden brown. Remove from the oven and cool to room temperature. Reduce the oven temperature to 325°F.
To make the filling: Place the cream cheese, sugar, and flour in the bowl of a stand mixer fitted with a paddle. Run the mixer at low speed until no lumps remain, about 4 minutes. Scrape the bowl and mix in the orange zest, salt, vanilla, and 1 egg. Scrape the bowl and add the rest of the eggs, one at a time, waiting until each egg is fully incorporated before adding the next. Mix in the sour cream and orange juice.
Measure out 1 1/4 cups of the batter and set aside. Pour the rest into the pan over the cooled crust. In a medium heatproof bowl, heat the pistachio paste with the water for 1 minute at half power in the microwave; stir to soften it and remove as many lumps as you can. Add half of the reserved filling and mix until smooth. Add the remaining reserved filling and mix completely.
Add the pistachio batter to the orange batter and mix until smooth for a uniform effect. Alternately, you can drop the pistachio batter by the tablespoonful in a ring around the cheesecake about 1" in from the edge, and swirl with a table knife for a decorative touch.
Bake the cheesecake for 45 to 50 minutes, until the edge of the cake is set 1" in from the edge. The middle should still jiggle when you nudge the pan; the center will look underbaked.
Turn off the oven and prop open the door. Set a timer for 1 hour. The cheesecake will slowly finish cooking during this time.
After 1 hour, take the cake out of the oven, cool to room temperature, and refrigerate until ready to serve. Before serving, decorate the top with chopped pistachio nuts and orange slices or candied orange peel.
Store any leftovers in the refrigerator for several days.
Tips from our Bakers
Want to make your own pistachio paste? The following recipe makes 1 generous cup of paste; use what you need in the recipe and refrigerate or freeze the rest.
1 1/3 cups (160g) shelled roasted pistachios, salted or not
6 tablespoons (74g) granulated sugar
4 to 6 tablespoons (57g to 85g) water
Blanch the nuts in boiling water for 15 to 20 seconds, then drain and rinse with cold water. Rub the nuts between layers of a clean dish towel; the friction will loosen the nuts’ skin, making them easier to peel. Peel the skin from the nuts.
Pulse the pistachios and sugar in a food processor until no large bits of pistachios are visible (the finer the grind, the smoother the finished paste will be).
Add 4 tablespoons (57g) water and pulse to combine. Add more water if necessary to make a smooth paste.
Store paste airtight in the refrigerator.
Note: Blanching and peeling the nuts results in a bright-green paste that looks great in your baked goods. Skipping this step yields a muddy brown paste that’s not as attractive; that said, feel free to skip those extra steps if the paste’s color won’t bother you.