Preheat the oven to 350 degrees F.
Line a heavy baking sheet with parchment paper or spray with cooking spray. In a medium bowl, mix flour and baking powder. Set aside.
In a large bowl or stand mixer, combine the sugar, butter, orange zest and salt. Mix until smooth.
Add eggs, 1 at a time and mix until just combined.
With the mixer on low, slowlly add the flour mixture and mix until just combined. Stir in cranberries and half of the white chocolate chips.
On the prepared baking sheet, form the dough into a log 12-inches long, 3-inches wide. Bake for 40 minutes. Remove and allow to cool complete, about 30 minutes.
Once cooled, place on a large cutting board, and use a sharp serrated knife to cut into 3/4-inch pieces. You want to cut across the shorter end, so your pieces will be about 3/4-inch x 4-inches. Place the biscotti back on the baking sheet, cut-side down and bake again for 15 minutes, until golden. Transfer the biscotti to a rack and cool completely.
Once cooled, melt the remaining white chocolate chips and shortening in a small bowl in the microwave for 30 seconds. Stir and then heat an additional 15 seconds until mostly melted. Stir until smooth, add orange extract and stir again to combine. Transfer the melted chocolate into a wide, shallow dish that is large enough to lay the biscotti in, but not too large that the chocolate will spread out too much to get a good amount of coverage when dipped in.
Lay out a large piece of wax paper. Dip the bottom of each piece of biscotti in the white chocolate, transfer to wax paper and allow to cool and set.