Preheat oven to 350ºF.
Line a large baking tray with parchment paper or a silicone baking mat and set aside.
In a small bowl, make your flax egg by combining 2 tbsp ground flax seeds and 6 tbsp warm water. Let sit for 5 minutes.
In a large mixing bowl, add in flax eggs and remaining wet ingredients and whisk well.
Add in all dry ingredients except pistachios and mix well until all ingredients are combined.
Fold in chopped pistachios and mix until well incorporated into the dough.
Using a spatula, separate your dough in half in your mixing bowl. Lightly oil your hands with olive oil and scoop out half the dough onto your baking tray. Form a cookie log with the dough, about 4.5 inches wide and do not press down too much. Try to create a rounded top with the biscotti log. Repeat for the other half of dough.
Brush your two cookie logs with olive oil and sprinkle a generous amount of cane sugar on top.
Bake for 40 minutes and let cool for about 10-15 minutes, or until they are completely cooled and ready to be cut.
Slice your biscotti with a chef's knife on a cutting board, then place back on your baking tray on one side and bake at 275ºF for 10 minutes. Remove from oven, flip biscotti on the other side and bake for another 10 minutes or until golden brown.
Melt the chocolate in the microwave with the coconut oil in 25-30 second increments until fully melted.
Drizzle the melted chocolate on top of your biscotti. Let the chocolate dry completely before serving.