Preheat your oven to 340F and grease one 12 cups bundt pan.
Cream the cream cheese, butter, sugar, and pistachio paste on high speed in a large bowl until light and fluffy, about 4-5 minutes. Make sure to scrape the sides and bottom of the bowl 2-3 times, or as needed.
Add the eggs, one at a time, waiting for each egg to fully incorporate before adding the next egg.
In a separate large bowl, mix the flour, potato starch, baking powder and chopped pistachios.
Reduce the speed to low, then add the flour in three parts, alternating with the sour cream.
Once you added the last part of the flour, use a rubber spatula to mix the flour into batter. This is the best way to make sure we are not over mixing.
Fill the greased pan with the batter and bake for 45-55 minutes, or until the top of the cake is golden brown and a toothpick comes out from the center of the cake with a few moist crumbs.
Remove the cake from the oven and allow the cake to set and chill in the pan for at least 45 minutes before inverting the cake. Inverting the cake too soon might cause the cake to collapse and some part to stick to the pan. However, if the cake cools completely in the pan it might get stuck to the pan as well.