Melt the chocolate and butter in a water bath, then add the walnuts and coconut butter. Leave the mixture in the freezer for 15-20 min.
Once it's thick enough, take it out, scoop spoonfuls of the mixture and form small bonbons with your hands.
Roll them in finely chopped walnuts and return to the fridge. Store in the fridge. Ingredients listed are for 12-15 bonbons.