Make the Coconut-Pineapple Filling:

1. Prepare the Coconut Filling: In a medium saucepan, combine the shredded coconut, pineapple juice, heavy cream, and rum (if using). Cook over medium heat, stirring occasionally, until the mixture is heated through and the coconut softens, about 3-5 minutes.
2. Cool the Mixture: Remove the mixture from the heat and allow it to cool for a few minutes. The texture should be slightly thickened.
3. Blend in White Chocolate: Add the chopped white chocolate to the warm coconut mixture. Stir until the chocolate melts completely, creating a smooth, creamy mixture. If you want extra sweetness, stir in a tablespoon of powdered sugar.

Shape the Truffles:

4. Chill the Mixture: Allow the coconut mixture to cool to room temperature. Then, refrigerate it for 45-60 minutes until it firms up and becomes easier to handle.
5. Form the Truffles: Once the mixture has chilled, use your hands or a small scoop to roll the mixture into balls, about 1 inch in diameter. Place the formed truffles on a parchment-lined tray.

Coat with Chocolate:

6. Melt the Semisweet Chocolate: In a microwave-safe bowl, melt the semisweet chocolate chips in 20-second intervals, stirring after each interval until smooth. You can also melt the chocolate over a double boiler.
7. Dip the Truffles: Using a fork or toothpick, dip each coconut ball into the melted semisweet chocolate, ensuring it’s fully coated. Let any excess chocolate drip off before placing the truffle back on the parchment paper.
8. Set the Chocolate: Allow the chocolate-coated truffles to set at room temperature for a few minutes, then place them in the fridge for about 15 minutes to fully harden.

Optional Final Touches:

9. Decorate the Truffles: Once the truffles are set, you can drizzle more melted white chocolate over them or roll them in additional shredded coconut for an extra tropical touch.