01 - Preheat the oven to 325°F. Line a standard 12-cup muffin tin with paper liners.
02 - In a mixing 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 at the bottom of each cup.
04 - In a separate mixing bowl, beat the softened cream cheese and sugar together using an electric mixer or whisk until completely smooth and free of lumps.
05 - Add the egg and vanilla extract to the cream cheese mixture. Mix until just combined — avoid overbeating. Gently fold in the sour cream until evenly distributed.
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 on the center rack for 18 to 20 minutes. The cheesecakes are done when the edges are set but the centers still have a slight jiggle.
08 - Remove the tin from the oven and allow the cheesecakes to cool in the pan at room temperature for 15 minutes.
09 - Transfer the cheesecakes to a wire rack to cool completely, then refrigerate for at least 1 hour to allow the filling to set fully.
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.