Make the truffles: In a small saucepan, heat heavy cream to almost a boil. In a medium bowl, add chocolate and peppermint, and pour hot heavy cream over. Whisk until combined. Fold in Thin Mint pieces and refrigerate for up to 2 hours. Scoop with a small ice cream scoop and place on a cooling rack over a baking sheet.
Make the ganache: In a small saucepan, heat heavy cream to a near boil. Place chocolate in a medium bowl and pour hot cream over it. Whisk to combine until smooth. Set aside to chill.
Decorate the truffles: Pour ganache over chilled truffles. Return to the fridge for 20 minutes to set. Melt the candy melts with the coconut oil. Drizzle over set truffles. Truffles will keep up to 5 days in the fridge.