Soak the cashews in water overnight (or for at least 2 hours). Drain and transfer to a high-powered blender
Turn the blender on to break up the nuts and form a paste. You’ll need to stop the blender, scrape the sides and bottom, and re-start several times.
Leaving the blender on, slowly pour the pure maple syrup and lemon juice through the hole in the top of the blender cover (Note: if there’s no hole in the cover, you can simply pour the maple syrup and lemon juice into the blender when it’s stopped). Continue running the blender, stopping to scrape the sides, until a thick frosting results. I used a Blendtec Blender and let it run on the whisk setting for the full duration 6 times, scraping the sides between each time.
Transfer to a container and refrigerate until ready to use.
Prepare the flax eggs:
To make the flax eggs, combine 3 tablespoons of ground flax seed and 9 tablespoons of lukewarm water in a small bowl. Allow mixture to sit for 10 to 15 minutes, stirring occasionally, until very thick and egg-like.
Add the almond flour, tapioca flour, baking soda, sea salt, cinnamon, nutmeg, and cardamom to a large mixing bowl. Stir together until well-combined (dry mixture).
In a separate bowl, whisk together the oil, pure maple syrup, cider vinegar, grated ginger, vanilla bean scrapings (or vanilla extract), and shredded carrot (wet mixture).
Transfer the flax eggs and the wet mixture to the bowl with the dry mixture and stir well to combine. The batter should be very thick and pasty.
Transfer the cake batter to the prepared pan, and smooth it out to create an even layer.
Bake on the center rack of the oven for 32 to 36 minutes, or until cake tests clean. Allow cake to cool for 30 minutes.
Release the mold from the springform pan and gently transfer cake to a cutting board. Spread the vegan cream cheese frosting over the surface and sides of the cake and decorate with chopped pistachios. Cut slices and serve.
*Use almond oil or grapeseed oil in place of avocado oil