Place cacao nibs, sugar, and coconut flakes into Thermomix bowl and mill 15 sec/speed 10.
Add vanilla, salt and coconut oil and warm min/50°C/speed 4.
Add rice puffs and mix 12 sec/Interval.
Press into square tin with removable base and place in the freezer.
To make topping place all ingredients except coconut flakes into Thermomix bowl and melt 6-7 min/60°C/speed 2, stopping and scraping down sides of bowl and lid as necessary. Blend 10 sec/speed 4.
Work quickly to spread on top of slice as it will set as it hits the cold base. Tap the tin on the bench to level the topping. Garnish with coconut flakes if using. Place in the fridge or freezer to set. Remove from tin completely to cut into squares, wiping knife between each cut.
These will store in the freezer really well, otherwise keep them in the fridge for up to 3 weeks.
To roast cacao nibs, place into a cold oven set to 180°C and roast for 10-12 minutes until fragrant. You can roast slower and longer if you desire. There is more flavour to be had if you roast slower!