Place the finely chopped white chocolate in a medium heatproof bowl. Set aside.
Heat the heavy cream in a small saucepan over medium heat until it just begins to simmer with small bubbles around the edges, about 3 minutes. Do not let it boil.
Pour the hot cream over the chopped chocolate and let it sit undisturbed for 2 minutes to soften the chocolate.
Whisk the mixture gently from the center outward until completely smooth and glossy. Add 2 tablespoons mango powder, softened butter, vanilla, and salt, whisking until fully incorporated.
Cover the bowl with plastic wrap pressed directly onto the surface of the ganache to prevent a skin from forming. Refrigerate for 2-3 hours until firm enough to scoop but not rock-hard.
Line a baking sheet with parchment paper. Using a small cookie scoop or spoon, portion the ganache into 1-inch balls and place on the prepared sheet. Refrigerate for 30 minutes.
Roll each portion between your palms into smooth spheres, working quickly to prevent melting. Return to the fridge for 15 minutes.
Melt the coating chocolate with coconut oil in a narrow, deep bowl, stirring until smooth. Using a fork or dipping tool, dip each truffle into the chocolate, tap off excess, and return to the parchment-lined sheet.
Immediately dust the tops with the remaining 1 tablespoon mango powder while the coating is still wet. Refrigerate for 20 minutes until set.
For a thicker coating, repeat the dipping process after the first coat has set, then dust with additional mango powder if desired. Store in the refrigerator until ready to serve.
