Preheat the oven to 350 degrees.

In a medium sized mixing bowl, stir together the flour, baking powder, baking soda, and salt. Set aside.

In a large mixing bowl, beat together the butter, sugar and vanilla together until light and fluffy. Add the eggs, beating one at a time. Then add both boxes of pistachio pudding, beat until well blended, scraping down the sides of the bowl as needed.

Mix in the flour mixture and the buttermilk alternately, starting and ending with the flour.

Prepare 2 loaf pans with nonstick cooking spray.

Divide the cake batter between the 2 loaf pans.

Bake at 350 degrees for 40-45 minutes or until a toothpick inserted in the center comes out clean.

Cool on wire racks for 10 minutes, then remove from pans and cool completely on wire rack.

Whisk together the confectioners sugar with vanilla and milk until smooth and lump free. Drizzle over the cakes.