Warm the cacao butter in a bain-marie (a bowl sitting in hot water) until liquid. You could do this step in a microwave or in a small pot over a very low heat as well if you prefer.
Stir in all the ingredients until well combined and pour into a silicone chocolate mould.
Place in the freezer for 5 minutes. Option to top with chopped pumpkin seeds or pistachios now - press them gently on the top.
Return to the freezer for another 20 minutes until set.
Notes
These matcha chocolates are best kept in the fridge, though they will stay firm at room temperature as well.