1. Prepare a large baking sheet with parchment paper. Preheat oven to 350 degrees
2. In a medium bowl, whisk flours, baking powder, and salt.
3. In the bowl of an electric mixer, mix butter and sugar on medium high speed for about three minutes or until light and fluffy.
4. Add one egg at a time and mix until blended. Add vanilla and orange zest and continue mixing to combine.
5. Reduce speed of mixer and add flour mixture in small amounts. When flour is incorporated, add macadamia nuts and cherries and mix until combined.
6. Transfer dough to a floured surface, If dough is too sticky, add flour in small amounts until you can handle the dough. Cut dough in half and roll each half into a 12 inch log.
7. Place dough logs on baking sheet about two inches apart. Place baking sheet in the oven and bake for 30 minutes. Rotate pan halfway through cooking.
8. Remove baking sheet from oven and cool for 30 minutes.
9. Transfer logs to a cutting board. With a serrated knife, cut log into 1/2 inch slices at a sharp diagonal. You should end up with biscotti that are 1/2 inch wide and five to six inches in length.
10. Place biscotti on baking sheet cut side down, return to oven, and bake for 10 to 15 minutes or until slightly browning. Place biscotti on a cooling rack and cool completely.
11. In a double boiler, melt white chocolate. Dip the bottom of each of the biscotti in the white chocolate and place on wax paper to dry