Line mini muffin pan with paper liners. Or you can use mini silicone cups. Place dulce de leche in a piping bag, or ziplock bag with one corner cut.
To melt the chocolate, place the chopped chocolate and coconut oil in a medium silicone (or plastic) bowl.
Microwave for 30 seconds at 50% power. Then stir well and put it back for 15 seconds at 50% power. Stir well and continue microwaving in 15-second increments at 50% power until the chocolate is fully melted, stirring well in between.
Place the melted chocolate in a piping bag, or using a small cookie scoop, pour about 1 tablespoon of chocolate into each cup.
Then pipe about 1 teaspoon of dulce de leche into each cup right in the center.
Top with the remaining melted chocolate to cover the filling. Tap the muffin pan on the counter to smooth out the top.
Let the chocolate set at room temperature for at least 30 minutes, or until fully set.
Store in an airtight container for up to 1 week at room temperature.