Whisk together the almond flour, almond slivers, coconut sugar, arrowroot, baking powder and salt in a large bowl. Add the water and extracts and stir well until everything is combined.
Preheat the oven to 350F.
Transfer the dough to a parchment-lined baking sheet. Shape it into a log (11 inches long x 2 ½ inches wide).
Bake for 20 minutes, until the log is set and has turned a light golden-brown.
Remove it from the oven and let it cool. Then chill in the fridge for at least 1 hour or up to overnight.
When ready to bake again, preheat the oven to 250F. Place the log onto a cutting board and cut into ½ inch slices. Place the slices on the baking sheet (cut side up), and bake for 20 minutes. Flip each biscotti and bake for another 20 minutes.
Turn off the oven and let the biscotti cool inside for 2 hours for a nice and crunchy cookie.
(Optional) When the cookies have cooled, melt the dark chocolate and coat the bottom of the biscotti. Place in the fridge for 20 minutes for the chocolate to set.
