Preheat oven to 350°F.
Line cookie sheet with parchment paper.
Using a stand mixer, combine sugar, butter, lemon zest, and salt.
Add the eggs one at a time, beating to incorporate.
Add flour and baking powder, and mix well.
Add pistachios and cranberries, and stir until combined.
Divide dough in half.
Working on a floured surface and using lightly floured hands, form each half into a loaf, approximately 10″x3″.
Place on prepared cookie sheet, and bake for 30 minutes, or until lightly golden brown.
Leaving oven on, remove cookie sheet from oven, and allow biscotti to cool for 15 minutes.
Using a butcher knife, cut the loaves into diagonal slices about 1/2″ thick.
Return slices to cookie sheet, cut side down.
Bake for 8 or 9 minutes, flip slices, and bake for another 8 or 9 minutes.
Place on baking rack to cool.
When cool, place white chocolate chips in a microwave-safe container.
Heat in microwave in 30 second increments, stirring after each, until fully melted.
Frost one cut side of each biscotti with melted white chocolate chips.
Place glazed biscotti in refrigerator to set the chocolate.