Line the bottom of a tall 6-inch or regular 7-inch springform pan with parchment paper.
Add all crust ingredients to a food processor or high-powered blender and blend. Add water as needed to get a sticky mixture. If using a blender, your batter might be a bit chunky, but as long as you don't have large pieces of nuts it should be ok.
Pour the crust mixture at the bottom of the lined pan and press with your fingers into an even layer. Place in the freezer to firm up while you prepare the filling.
Rinse and drain the cashews, if soaking. You can skip the soaking step if using a high-powered blender like a Vitamix. Add to blender with the rest of filling ingredients. Blend for 1 minute or more until you get a smooth mixture. Taste test and add more maple syrup if you prefer your cake sweeter.
Take pan out of the freezer and pour the filling over the crust. Return to the freezer and chill for at least 2 hours until firm.
Decorate with shaved chocolate, if desired, and enjoy! Store leftovers in the fridge for up to a week or in the freezer for up to 3 months.
