Preheat your oven to 325°F and generously spray a 12-cup muffin tin with cooking spray to prevent sticking.
Make the crust by combining graham cracker crumbs, melted butter, and 1/4 cup sugar in a medium bowl until the mixture resembles wet sand and holds together when pressed.
Press about 2 tablespoons of the crumb mixture firmly into the bottom of each muffin cup, using a small glass or spoon to create an even, compact layer.
Beat the softened cream cheese and 1/2 cup sugar with an electric mixer on medium speed until completely smooth and creamy, about 2 minutes, scraping down the sides as needed.
Add eggs one at a time, mixing just until incorporated after each addition, then blend in the vanilla extract and sour cream until the batter is smooth and uniform.
Pour the cheesecake batter over the prepared crusts, filling each cup nearly to the top, then press one chocolate truffle into the center of each until submerged.
Bake for 18-22 minutes until the edges are set but the centers still jiggle slightly when the pan is gently shaken.
Let the cheesecakes cool completely in the pan on a wire rack before carefully removing them with a butter knife – they will firm up as they cool.