Line a sheet pan with parchment paper.
In a microwave-safe bowl, place white chocolate; microwave until partially melted, about 30 seconds.
In a microwave-safe bowl, place heavy cream and coconut extract; microwave in 30-second intervals until steaming. Pour over partially melted white chocolate, and stir until fully melted. Place in fridge to set, about 1 hour.
Using a 1-inch spring-loaded scoop, scoop white chocolate mixture onto prepared pan. Press 1 whole macadamia into the center of each round. Refrigerate 1 hour more.
Roll each truffle in confectioners’ sugar, and using your hands, roll into balls. Dip truffles in melted bittersweet chocolate. Sprinkle with chopped nuts, if desired. Refrigerate until set.