Place candy canes into Thermo bowl and chop 1 sec/speed 5. If the pieces are still too large, chop another 1 sec/speed 5. Repeat as needed. You are aiming for pieces, not dust. (I usually just place the candy canes into a ziploc bag and bash them with a rolling pin, it is just as quick and a lot easier.)
Remove most of the candy canes from bowl and set aside.
Place dark milk chocolate and peppermint oil into Thermomix bowl and melt 45 min/37°C/speed 2. Occasionally scrape down sides of bowl as needed.
Pour onto silicone mat or piece of baking paper and spread with a spatula as thinly as possibly.
Sprinkle with the chopped candy canes, pushing the larger pieces into the chocolate so that they ‘stick’. You can also add nuts, dried rose petals or freeze dried berries or other fruit of choice at this stage.
When the bark has set, drizzle the melted white chocolate and coconut oil over to decorate.
Melt the white chocolate if using with the coconut oil in a non ceramic bowl in the microwave, or over a double boiler. Ceramic will hold the heat too much and potentially burn your chocolate. Stir together before using. There is no point in trying to melt 50g of chocolate in the Thermomix, it will just drive you mad and not really accomplish what you need.