Preheat oven to 325 degrees F (160 degrees C). Prepare two loaf pans by lining each with parchment paper, spraying with cooking spray, and dusting them with all-purpose flour. Set aside.
In a medium bowl, combine the All-Purpose Flour (1 1/2 cup), Cake Flour (1 1/2 cup), Baking Powder (1 teaspoon), and Salt (1 teaspoon). Set aside.
Finely grind 1 cup of the Pistachios (1 3/4 cup) in a food processor, and finely chop the other 3/4 cup of pistachios.
In the bowl of an electric mixer, fitted with the paddle attachment, beat together the Unsalted Butter (1 1/4 cup), Cream Cheese (3/4 cup), and ground pistachios. Allow the ingredients to cream together for about 5 minutes on medium-high. Reduce speed to low.
Slowly stream in the Granulated Sugar (3 cup) and continue to beat on medium-high until the mixture is light and fluffy, about 3 minutes. Scrape down the sides and bottom of the bowl to ensure even mixing.
Once the mixture is completely smooth, add the Large Egg (6), one at a time, mixing well after each addition. Add the Vanilla Extract (2 teaspoon) and mix once more.
Reduce speed to low, and carefully add the reserved flour mixture; beat until just combined. Do not overmix the batter at this point. Fold in the chopped pistachios.
Divide the batter among the prepared pans, and smooth out the tops with a rubber spatula. Bake for about 1 hour and 35 minutes, rotating the pans halfway through baking.
For the glaze, combine the Powdered Confectioners Sugar (1 1/4 cup), Heavy Cream (3/4 cup), and Lemon Juice (1 teaspoon) in a bowl. Whisk until completely smooth.
Let the cakes cool on a rack for about 20 minutes. Unmold and discard the parchment paper. Allow the cakes to cool completely before frosting and topping with additional chopped Pistachios (1/2 cup). Serve right away.