Pre-heat the oven to 350°F.
In a small bowl, sift together the flour, baking powder and salt; set aside.
In a medium bowl. cream together butter, sugar and vanilla extract; continue creaming very well until light and fluffy.
Beat in the eggs, one at a time, beating well after each addition.
Fold in the dry ingredients, just until the flour is incorporated; work the dough as little as possible for the lightest biscotti.
In the final few turns of folding in the flour, just when it's almost completely incorporated, add the cranberries and pistachio nuts.
Form the dough into two 3-inch-wide logs; place 6 inches apart on a parchment lined cookie sheet.
Place in oven and bake for about 30 minutes.
Remove the biscotti from the oven and let cool for about 10 – 15 minutes before cutting the biscotti on a diagonal into ¾-inch-thick slices.
Place the biscotti back on the parchment lined cookie sheet, return to oven and reduce the temperature to 300°F.
Bake for an additional 15 minutes before turning the cookies over and baking for an additional 10 minutes.
Remove from oven and cool completely on a wire rack.
