01 - Preheat oven to 325°F. Line a 12-cup mini muffin tin with paper liners.
02 - Mix crushed chocolate sandwich cookies with melted butter in a medium bowl until combined. Spoon about 1 tablespoon of mixture into each liner, pressing firmly to create an even crust.
03 - Bake crusts for 5 minutes. Remove from oven and allow crusts to cool slightly.
04 - Beat cream cheese and granulated sugar in a large bowl until smooth. Add egg, vanilla extract, sour cream, and salt. Mix until just combined.
05 - Distribute filling evenly over each crust, using about 1 heaping tablespoon per cup. Bake for 13 to 15 minutes until centers are just set but still slightly jiggly.
06 - Cool the cheesecakes in the tin for 20 minutes, then transfer to a wire rack. Refrigerate for at least 45 minutes until thoroughly chilled.
07 - Melt white chocolate in a microwave-safe bowl using 20-second intervals, stirring between each, until smooth.
08 - Pipe or spoon a rounded dollop of melted white chocolate onto each cheesecake to create a ghost shape, extending a slight 'tail' at the bottom.
09 - While white chocolate is still soft, gently press mini chocolate chips for eyes and regular chocolate chip halves for mouths.
10 - Refrigerate cheesecakes until the chocolate decorations are set. Serve chilled.