Dump the pistachios into a food processor and chop them until they are very fine, with mostly no large pieces. Reference the picture in the post above to see how ground down they should be.
Preheat the oven to 350°F
Stir the milk and sour cream (or yogurt) together in a small cup and microwave them for 10-15 seconds to bring them to room temperature. Then stir in the lemon zest.
In a stand mixer fitted with the paddle attachment, cream the butter and sugars together on medium-high speed for 3 minutes. Scrape down the sides of the bowl and add the egg, egg white, and vanilla. Then continue beating on medium-high for another 3 minutes, until the mixture is light and fluffy.
In a separate bowl, combine the flour, baking powder, baking soda, salt, and ⅔ cup of the chopped pistachios. Reserve remaining pistachios for garnishing.
Turn your mixer on the lowest setting possible and add in ⅓ of the flour, then slowly stream in all of the milk/yogurt, and lastly the remaining flour. Once you've added the last of the flour, paddle for 5-10 seconds seconds, then turn off your mixer and finish folding the batter by hand until the flour is just combined. This will prevent any over-mixing. The batter will be thick.
Grease your bundt pan with shortening and a dusting of flour. Pour the batter in and then bake for 30-35 minutes, or until the cake is fully set. If baking in a 10-cup bundt pan, increase the time to 55-65 minutes.
Once the cake is done and out of the oven, let it rest in the pan for 10-15 minutes before turning it over onto a cooling rack.
To make the glaze, start by whisking the cream cheese and butter together--this may be a little difficult to do a first but just just a lot of force. Then, add the powdered sugar, milk, vanilla, salt, and lemon zest. Continue whisking until the mixture is smooth.
Pour the glaze over a completely cool bundt cake. Garnish with remaining pistachios. Enjoy!