- Preheat oven to 290°F. Prepare the mini bundt pans by spraying with cooking spray and dusting them with flour. Set aside.
- In a medium bowl combine the flours, baking powder, and salt. Set aside.
- In the bowl of an electric mixer, fitted with the paddle attachment, beat together the butter, cream cheese, and pistachio butter. Allow the ingredients to cream together for about 5 minutes, on medium high.
- Reduce speed to low. Slowly stream in the granulated sugar 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 eggs, one at a time, mixing well after each addition. Add the vanilla extract 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 granulated pistachios.
- Divide the batter among the prepared pans, and smooth out the tops with a rubber spatula.
- Bake for about 60 minutes, rotating the pans halfway through baking. The loaves should be golden brown and a toothpick inserted in the middle should come out clean.
- Let the cakes cool on a rack for about 20 minutes. Unmold and allow the cakes to cool completely before glazing.
- To make the glaze: Combine the powdered sugar, milk, and lemon juice in a bowl. Whisk until completely smooth. Adjust the consistency by adding more milk if necessary. Dip the top of the mini pound cakes and sprinkle with pistachio brittle crunch before the glaze sets up.