Set oven rack in the middle and preheat oven to 325° F/165° C.
In the bowl of the stand mixer, cream together the butter and the cream cheese. Add the sugar a little at a time, mixing on medium speed until light and fluffy.
Add the eggs, one at a time, mixing on low just until the yolk is no longer visible. Don’t overmix.
In the medium bowl, sift together the flour and the salt. Add ⅓ of the flour and salt to the butter mixture and mix on low just until blended. Add the vanilla and ½ the Irish cream and mix in, then ⅓ of the flour and mix, the remaining Irish cream, and finally the rest of the flour. Be gentle. Don’t over mix, or the cake will be tough and lose volume. You can also do this part by hand using a spatula to fold in the flour and Irish cream.
Gently fold in the pistachios.
Pour into the prepared tube/loaf pan(s) and smooth the top of the batter with a spatula. Bake for 1 hour 15 minutes (loaf pans) or1 hour 45 minutes (tube pan). Use a long bamboo skewer to test doneness. Skewer should come out dry, but may have a few crumbs clinging. Remove from oven and cool in the pan on a wire rack for 15 minutes. Remove from pan and cool completely on the wire rack.
In the small bowl, whisk together the confectioners sugar and the Irish cream. Add a little milk at a time, adding just enough to make the glaze easy to pour. Drizzle over the cake and allow to rest a few minutes, then serve.