Preheat the oven to 350ºF. Line 36 muffin cups with paper liners. Set aside.
In a medium bowl, combine crushed graham crackers with 4 ½ tablespoons granulated sugar. Mix in melted butter until evenly coated. Divide graham mixture among prepared muffin cups, using about a heaping tablespoon for each. Press down firmly into an even layer and bake in the oven for 5 minutes. Remove from the oven and let cool while preparing the filling.
In a small bowl, whisk together 1 ½ cups granulated sugar with 3 tablespoons flour. In the bowl of a stand mixer fitted with the paddle attachment, combine softened cream cheese and sugar mixture on low speed until smooth. Add eggs one at a time, blending on low speed, and mixing just until combined after each addition. Scrape down the sides of the bowl as needed. Add vanilla, sour cream, and heavy cream and mix until just combined. Divide the mixture among the muffin cups, filling each nearly full. Bake in the oven 20-23 minutes or until centers are no longer wet looking but still jiggle slightly. Remove from the oven and allow to cool 1 hour. Cover loosely with plastic wrap and transfer to the refrigerator and chill 2 hours.
While the cheesecakes are cooling, prepare the topping. Have all your ingredients ready before beginning, as things tend to move quickly with caramel.
In a heavy-bottomed 3 quart saucepan, heat sugar and water over medium-high heat, whisking constantly as the sugar dissolves. Once the mixture reaches a boil, stop whisking and allow to boil until it reaches a dark amber color, swirling the pan occasionally. Once the mixture is a dark amber color, immediately add butter and whisk until it has completely melted. Remove from the heat, wait 3 seconds, and slowly and carefully pour in cream, whisking to combine. The mixture will bubble vigorously and begin to smooth out. Whisk until the mixture is smooth. Allow the caramel to cool several minutes, then pour into a glass jar or container to cool.
Spoon cooled caramel onto cooled cheesecakes and serve immediately or refrigerate.