For the walnut flour - make you own by adding raw walnuts to your food processor and breaking down into a flour. That, or you could try replacing the walnut flour at a one to one ratio with
almond flour. For a grain-based option, try the base from
this recipe.
For the coconut nectar - other liquid sweeteners could be used like honey (no longer vegan) or date syrup.
Will keep for 4 days in the fridge. Can be cut into squares and then frozen for up to 1 month.