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.
Chocolate chips are designed to be less melty than regular chocolate (since they need to retain their shape when baked), so arguably, it's better to use a chocolate bar. However, I often use chocolate chips with no issues, so that's an option if it's more convenient or if that's what you have on hand.
You can keep these clusters in an airtight container at room temperature (up to 70°F) for up to four days. For longer storage and up to a week, or if your house is very warm, 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.