Add pecans/walnuts to a food processor and blitz until coarse crumbs. Add rest of base ingredients and process until combined.
Press into the base of a lined loaf tin (I used a 28x13cm rectangular tin)
For the filling, add all ingredients to a mixing bowl and mix until combined. Mix in flavourings if desired (see notes).
Firmly press filling into the loaf tin.
For the chocolate topping, melt the cacao butter in a saucepan over low heat until just melted. Add rest of ingredients and mix until combined. If there is still oil floating on the top, emulsify by using a whizz stick.
Pour chocolate on coconut filling and decorate as desired.
Set aside in the fridge for 6 hours or until the coconut is firm (you'll know when it's set when you can press the chocolate and there is no indentation.