Preheat the oven to 325°F. Line a muffin tin with paper liners.
In a medium bowl, combine the graham cracker crumbs, 1/4 cup sugar, and melted butter. Mix until well combined. Press about 1 tablespoon of the mixture into the bottom of each muffin cup to form a crust.
In a microwave-safe bowl, melt the chocolate chips in 30-second intervals, stirring in between until smooth. Let cool slightly.
In a large mixing bowl, beat the cream cheese and 1/2 cup sugar until smooth and creamy. Add the vanilla extract and mix well. Add the eggs one at a time, mixing well after each addition. Stir in the sour cream and flour until just combined.
Pour the melted chocolate into the cream cheese mixture and mix until fully incorporated.
Divide the cheesecake batter evenly over the crusts in the muffin tin, filling each cup about 3/4 full.
Bake for 20-25 minutes or until the edges are set but the centers are still slightly jiggly. Remove from the oven and let cool in the pan for 10 minutes before transferring to a wire rack to cool completely.
Refrigerate for at least 2 hours before serving.