Preheat oven to 350 degrees. Line a baking sheet with parchment paper.
Cream the butter. Add the sugar, lemon zest, vanilla and salt. Mix until very creamy and well combined.
Add the eggs one at a time, beating after each egg is added.
In a separate bowl, whisk the flour and baking powder.
Add the flour mixture to the butter/sugar mixture in thirds. Beat until just blended.
Stir in the pistachio nuts and cranberries.
Form the dough into two logs approximately 1 1/4 inches high x 15 inches long. The dough will be quite sticky.
Bake the logs for 30 to 35 minutes or until golden brown.
Reduce oven temp to 300 degrees. Remove from the oven and cool for about 20 minutes or until cool enough to handle. Place the log on a cutting board and using a serrated knife cut into inch one inch thick slices.
Place the slices flat side down and bake for another 12 to 15 minutes until firm and golden brown. Half way through the second bake, flip the cookies so both sides get crispy.
Cool completely on a rack. Store in an airtight jar.