Preheat your oven to 350°F (175°C). To waterproof your pan for the water bath, wrap the outside of a 9-inch springform pan with two layers of heavy-duty aluminum foil, ensuring it goes all the way up the sides.

In a medium bowl, combine the graham cracker crumbs, shredded coconut, and 2 tbsp granulated sugar. Pour in the melted butter and stir with a fork until all the crumbs are evenly moistened.

Press the mixture firmly and evenly into the bottom and about 1-inch up the sides of the prepared springform pan. Use the bottom of a glass to pack it tightly. Bake for 10 minutes. Remove and let it cool on a wire rack while you prepare the filling.

Reduce the oven temperature to 325°F (160°C).

In a large bowl using a handheld or stand mixer, beat the softened cream cheese on medium speed for about 2-3 minutes until completely smooth and free of lumps. Scrape down the sides and bottom of the bowl.

Add the 1 1/4 cups of granulated sugar and beat on medium-low speed until combined and smooth. Add the room temperature sour cream and vanilla extract, mixing until just blended.

With the mixer on low speed, add the room temperature eggs one at a time, mixing until just combined after each addition. Do not overmix, as this can cause cracks.

Gently fold in the well-drained crushed pineapple with a rubber spatula. Pour the filling into the cooled crust and spread evenly.

Place the foil-wrapped springform pan inside a larger roasting pan. Carefully pour hot water into the roasting pan until it reaches about halfway up the sides of the springform pan. This water bath is crucial for a creamy, crack-free cheesecake.

Bake for 65-75 minutes. The cheesecake is done when the edges are set, but the center 2-3 inches still have a slight jiggle. Turn off the oven, crack the oven door open, and let the cheesecake cool in the oven for 1 hour. This gradual cooling process also prevents cracking.

Remove the cheesecake from the oven and the water bath. Let it cool completely at room temperature on a wire rack. Once cooled, cover loosely with plastic wrap and refrigerate for at least 6 hours, or preferably overnight.

Drain the can of pineapple chunks, reserving 2 tablespoons of the juice. In a small saucepan over medium heat, melt the butter. Stir in the brown sugar, reserved pineapple juice, and optional dark rum until the sugar is dissolved.

Add the pineapple chunks and bring to a simmer. Cook for 5-7 minutes, stirring occasionally, until the sauce has thickened into a syrup. Remove from heat and let the topping cool completely before using.

Once the cheesecake is fully chilled, run a thin knife around the edge and carefully release the springform pan's side. Spoon the cooled caramelized pineapple topping over the cheesecake. Garnish with toasted coconut flakes just before serving.