Base: blend all base ingredients in a food processor or blender until it forms a dough that holds together between your fingers when pinched. Press into a pie or tart tin lined with biodegradable wrap.
Filling: blend all ingredients excluding the arrowroot, yacon root powder and lemon zest in a high speed blender until super creamy and smooth, then add the yacon powder at the last moment (it will thicken the mix, so don't add it too early). Pour 1/2c of the liquid into a bowl with the arrowroot and stir until completely combined. Pour remainder of the liquid into a pot and heat on low, then slowly pour in the arrowroot mixture whilst stirring, until the filling becomes thick and gooey. Stir through the lemon zest, then pour everything into your base and place in the fridge to set overnight.
Meringue: blend coconut and cashews in a high speed blender until super silky smooth, scraping down the sides if needed. Then with the motor on low, pour in the coconut oil slowly until it emulsifies into the cream. Pour into a bowl and place in the fridge to set overnight with the pie.
The next day, whisk the cream with a fork until light and fluffy, then dollop on top of your pie (remove it from the tin and biodegradable wrap first). Place back in the fridge for an hour to set, or in the freezer for a quick set. Top with lemon zest, then serve.