Preheat oven to 150 Celsius and line a baking sheet with baking paper. Spread the pistacchios and toast them for about 8 minutes not more - be very careful, they burn very easily. When ready, remove them, and set aside. Leave the baking paper on, you can reuse it for the biscotti.Whisk the flour, the light brown sugar, the salt, the cinnamon and the baking soda together in a mixing bowl. Add the cold, cubed butter and with your fingers until the mixture is crumbly.
Add the two handfuls of cranberries and two handfuls of the toasted whole pistacchios.
Beat 3 eggs in a small bowl and add them to the bowl.
Mix everything together with a wooden spoon or spatula.
Remove the dough from the bowl and turn it out on a lightly floured surface. With floured hands knead the dough for 6-7 times. It should be soft and lightly sticky. If it's too sticky and feels wet add more flour with a tablespoon - as many as you need to make it right.
Divide the dough in two, place both on the baking tray, next to each other, leaving 5-10 cm gap between them. With your hands, simply press them down and form a flat rectangular shape, around 2-3 cm thick.
Brush the tops with egg wash.
Bake them for 25-30 minutes. Depending on your oven, it can take a little more or less - they are ready when they are golden brown on the surface. Use a toothpick to check if they are baked on the inside too. Letting them cool for 10 minutes.
Cut the biscotti into 2-2.5 cm wide slices.
Melt chocolate above boiling water in a heat resistant bowl.
Roughly chop the remaining pistachios or use a food processor to do this. I just used a clean cloth and a rolling pin.
Dip one end of each biscotti into the melted chocolate (around 1/3 of it) and sprinkle with the toasted, chopped pistachios.