01 - Preheat the oven to 325°F. Line a standard 12-cup muffin tin with paper liners and set aside.
02 - In a medium bowl, combine the graham cracker crumbs, melted butter, and sugar. Stir until the mixture resembles wet sand and holds together when pressed.
03 - Divide the crumb mixture evenly among the 12 lined muffin cups. Using the back of a spoon or a small measuring cup, press firmly to create a compact, even crust layer.
04 - In a large bowl, beat the softened cream cheese and sugar together using an electric mixer until completely smooth and creamy, about 2 minutes. Scrape down the sides of the bowl as needed.
05 - Add the egg and vanilla extract to the cream cheese mixture. Beat on low speed until just incorporated. Gently fold in the sour cream with a spatula until evenly combined. Avoid overmixing.
06 - Spoon or pipe the cheesecake filling evenly over each prepared crust, filling each cup nearly to the top. Smooth the surfaces with a small spatula.
07 - Bake for 18 to 20 minutes, or until the edges are set and the centers still have a slight jiggle. The cheesecakes will continue to firm up as they cool.
08 - Remove from the oven and allow the cheesecakes to cool in the muffin tin for 15 minutes at room temperature.
09 - Transfer the cheesecakes to a wire rack to cool completely, then refrigerate for at least 1 hour to fully set before adding toppings.
10 - Top each mini cheesecake with your choice of fresh berries, lemon curd, melted chocolate, caramel sauce, chopped nuts, crushed cookies, or fruit preserves. Serve chilled.