Preheat the oven to 350 degrees F.
Line a baking sheet with parchment paper and set aside.
Place the flour, baking powder and pistachios in a large bowl and stir to combine.
In a medium sized bowl, whisk together the sugar, eggs, melted butter, vanilla extract and lemon zest.
Add the wet ingredients to the flour mixture and stir with a wooden spoon until combined.
Fold in the chopped Amarena cherries.
Divide the biscotti dough in half.
Dust your hands and work surface with flour and roll 1 portion at a time into a 12 inch log.
Transfer the logs to the prepared baking sheet.
Brush the biscotti logs with the beaten egg white.
Bake in preheated oven for 25 minutes.
Remove from the oven and allow to cool for 10 minutes.
Transfer the biscotti logs, one at a time, to a cutting board and slice diagonally to about 3/4 inch pieces.
Repeat with the remaining log.
Return the sliced biscotti to the baking sheet, stand them upright and bake for an additional 15 minutes.
Remove the biscotti from the oven, allow to cool and enjoy with your favourite hot beverage.