Pre-line a tray with grease-proof paper and keep aside in freezer/fridge. (A cold tray will help the chocolate to set).
Melt cacao butter in a heat-proof bowl by placing on top of a second heat-proof bowl of hot water. Stir until melted.
In a mixing bowl combine melted cacao butter, cacao powder and chosen sweetener. Place in refrigerator for 2 -3 minutes to allow to slightly thicken.
Stir in nuts and mix to coat well.
Spoon tablespoon portions into individual clusters onto your pre-chilled tray. You can also spoon into mini patty cases.
Sprinkle with cacao nibs if using.
Place in refrigerator until chocolate is set.