Place the chocolate pieces in a medium microwave-safe bowl. Melt them in two or three 30-second sessions, stirring after each session.
Use a rubber spatula to mix in the coconut oil and sweetener. Mix until smooth.
Add the coconut flakes and mix to coat them thoroughly with the melted chocolate.
Spoon the mixture into the paper liners.
Freeze for 15 minutes to set, then serve.
Video
Notes
If you don't mind the slight bitterness of extra-dark chocolate, or if you use sweeter chocolate, you might not need to add a sweetener at all. When I make this recipe with 70% cacao chocolate, I don't add a sweetener.
You can keep the leftovers in an airtight container at room temperature for up to four days. For longer storage and up to a week, refrigerate them in an airtight container. You can also freeze these clusters in a single layer in a freezer bag for up to three months.