Make the chocolate macadamia nut crust: Position a rack in the center of the oven and preheat to 350 degrees F; remove the side from a 9-by-3-inch springform pan; trim a 9-inch cardboard circle cake circle so that it fits within the curved lip of the bottom of the springform pan; cover the bottom of the pan with a piece of aluminum foil, leaving a 2-inch overhang all around the edge; carefully attach the side of the pan (lining the bottom of the pan this way will give the cheesecake an even flat base, making it easy to remove from the pan).
In a medium bowl, stir together the chocolate wafer crumbs, ground macadamia nuts, and toasted coconut; add the melted butter and mix well; press the mixture evenly onto the bottom of the prepared pan.
Bake for 10 to 12 minutes, until the crust is puffy and bounces back when gently presses with a finger; cool on a wire rack.
Prepare the coconut topping: In a medium bowl, using a wire whisk stir together the toasted coconut, flour and salt; add the butter cubes and with your fingers toss to distribute thoroughly; chill until ready to bake the cheesecake.
Make the filling: Position a rack in the lower third of the oven and reduce the oven temperature to 325 degrees F; using two large pieces of heavy duty aluminum foil, tightly wrap the outside of the pan.
In a medium saucepan combine the milk and the toasted coconut and bring to a boil; reduce the heat and simmer for 5 minutes; remove the pan from the heat and cover; steep the mixture for 30 minutes; strain the coconut milk, pressing the solids to extract all of the coconut; you should have 3/4 cup of liquid.
In the 4 1/2-quart bowl of a heavy-duty electric mixer using the paddle attachment, beat the cream cheese at low speed for 1 minute, until creamy; gradually add the sugar in a steady stream and beat at medium speed until blended; add the cornstarch; scrape down the side of the bowl, and beat 30 seconds longer; at medium-low speed, one at a time, add the eggs, beating well after each addition; gradually add the strained coconut milk and beat until blended; beat in the vanilla and the rum.
Pour the filling into the prepared pan; sprinkle the white chocolate chunks evenly over the filling; sprinkle the prepared coconut topping over the center of the cheesecake, leaving a 1-inch plain border around the rim of the cheesecake.
Place the cheesecake in a high-sided roasting pan on the lower rack of the oven; pour boiling water into the roasting pan so that the water comes half way up the side of the springform pan; bake the cheesecake for 70 to 80 minutes, until the sides are puffy and the center quivers; leave the cheesecake in the pan in the oven and turn off the oven; prop open the door of the oven with a wooden spoon and allow the cheesecake to cool down slowly in the oven for 30 minutes.
Remove the cheesecake from the roasting pan and remove the foil from around the outside of the springform pan; run a thin-bladed knife around the inside of the pan to release the cheesecake from the side of the pan; this will prevent the top of the cheesecake from cracking; cool the cheesecake in the pan set on a wire rack; refrigerate uncovered for at least 8 hours or overnight.
Garnish the cheesecake: Run a thin-bladed knife around the inside of the pan to release the cheesecake from the side of the pan; unclamp and remove the side of the springform pan; gently press the chocolate wafer crumbs onto the side of the cheesecake; dust the top with confectioner's sugar and decorate with white chocolate curls.
Slide a metal cake spatula under the cheesecake to loosen it from the bottom of the springform pan; slide two long metal cake spatulas underneath the cheesecake and transfer it to a serving plate.
Cut the cheesecake with a sharp, thin-bladed knife, dipping the blade in hot water and wiping it dry after each slice.