Preheat oven to 375° F. Coat a baking sheet with parchment paper or a silicone baking mat.
In a clean dry food processor or blender, blend your pistachios until as smooth as possible (it's fine if there are a few larger pieces).
In a bowl, add gluten-free flour, almond flour, sugar, blended pistachios, tapioca flour, ground flaxseeds, baking powder, and salt. Stir with a fork until fully combined.
Mix butter into dry ingredients with a fork. Add spinach water and flavor extracts, and mix until crumbly dough forms. Fold in cranberries.
Form a long cylindrical log, top with pistachios and cranberries, and press them in slightly so they don't fall off. Bake for 30 minutes.
Remove the biscotti log and let cool, then chill in the fridge for 1-2 hours. Chilling is technically optional, but as the loaf hardens up you will be able to slice it easier and neater.
When the biscotti loaf is done cooling, preheat oven to 250° F. Slice thinly, and lay slices down on a lined baking sheet. Bake for 30 minutes, flipping halfway.
Turn off the oven and do not open, leaving biscotti to slowly dry out for at least 4 hours. I like to leave mine in the oven overnight. This allows the heat from the oven to slowly suck out all the moisture, allowing you to get that classic dry crunchy texture.
You can dip one end of each biscotti in melted chocolate or carob bar.