Line a large baking sheet with parchment paper or a silicone baking mat and set aside.
Place white chocolate in a microwave-safe bowl. Microwave in 20-second intervals, stirring thoroughly after each burst, until completely melted and smooth (about 1-2 minutes total).
Pour the melted white chocolate onto the prepared baking sheet and use an offset spatula to spread it into an even layer about 1/4-inch thick.
Immediately scatter the chopped dried mango evenly over the chocolate, pressing gently so the pieces adhere to the surface.
Sprinkle toasted coconut and flaky sea salt over the top if using, distributing them evenly across the bark.
Tap the baking sheet firmly on the counter 2-3 times to release any air bubbles and help the toppings settle into the chocolate.
Let the bark set at room temperature for 1-2 hours, or until completely firm and no longer glossy.
Once set, break the bark into irregular shards using your hands. Store in an airtight container.
