Step 1: Prepare the Crust

1. Preheat your oven to 325°F (160°C) and line a muffin tin with paper liners.
2. In a mixing bowl, combine the graham cracker crumbs, melted butter, and granulated sugar. Mix until the texture resembles wet sand.
3. Spoon about 1 tablespoon of the crust mixture into each muffin cup. Use the back of a spoon or a flat-bottomed glass to press the crust firmly into the bottom of each liner.
4. Bake the crusts for 5 minutes, then set aside to cool slightly while you prepare the filling.

Step 2: Make the Cheesecake Filling

1. In a large mixing bowl, beat the softened cream cheese and sugar together until smooth and creamy, about 2-3 minutes.
2. Add the sour cream, egg, and vanilla extract, and mix until just combined.
3. Sprinkle in the flour and mix gently to avoid overbeating, which can lead to cracks.
4. Spoon the cheesecake filling evenly over the crusts in the prepared muffin cups, filling each about ¾ full.

Step 3: Add the Pineapple Topping

1. Cut each pineapple ring in half so they fit neatly on top of each cheesecake.
2. Sprinkle a small amount of brown sugar over each pineapple slice to help it caramelize in the oven.
3. Place a halved pineapple ring on top of each filled muffin cup.

Step 4: Bake and Cool

1. Bake the mini cheesecakes at 325°F (160°C) for 18-20 minutes, or until the centers are just set. They may appear slightly jiggly, which is fine as they will firm up while cooling.
2. Turn off the oven, crack the door slightly, and allow the cheesecakes to cool for 10 minutes in the oven to prevent cracking.
3. Remove from the oven and let the cheesecakes cool completely on a wire rack.
4. Once cooled, refrigerate for at least 2 hours or until thoroughly chilled and set.

Step 5: Garnish and Serve

1. Before serving, drizzle each cheesecake with caramel sauce to enhance the flavor and add a glossy finish.
2. Serve immediately, or keep refrigerated until ready to enjoy.