Make Pineapple Filling/Topping: Stir cornstarch and water until dissolved. In a saucepan, cook pineapple chunks, brown sugar, and pineapple juice over high heat for 18-25 minutes until liquid reduces to a syrupy consistency. Add cornstarch slurry and cook for 1-2 minutes until thickened. Stir in vanilla and rum, then cool in the fridge.
Make Crust: Preheat oven to 350°F. Spray a 9-inch springform pan and line the bottom with parchment paper. Mix melted butter with graham crumbs and press into the pan. Bake for 10 minutes and set aside.
Make Cheesecake Filling: Beat softened cream cheese with sugar until creamy. Add eggs one at a time, then mix in vanilla, sour cream, and rum. Stir until smooth.
Prepare Water Bath: Boil water in a large pot. Place the springform pan inside a 10-inch cake pan, then set in a roasting pan. Pour boiling water into the roasting pan until it reaches 2 inches deep.
Assemble Cheesecake: Pour half the cheesecake batter into the pan. Add 1/3 of the pineapple filling. Pour the remaining batter on top and smooth out.
Bake Cheesecake: Bake at 350°F for 1 hour 25 minutes to 1 hour 45 minutes. The center should have a slight wobble, and the knife should come out clean from the edge. Let cool in the oven for 1 hour.
Cool Cheesecake: Remove from the oven and let cool to room temperature. Refrigerate for at least 6 hours or up to 1 day.
Make Whipped Cream: Dissolve gelatin in water and microwave for 5 seconds. Beat whipped cream ingredients, then add gelatin mixture. Beat until stiff peaks form.
Serve Cheesecake: Remove the cheesecake from the springform pan. Top with pineapple topping and whipped cream. Garnish with maraschino cherries.
Store Leftovers: Store leftovers in an airtight container in the fridge for 3-4 days.