01 - Preheat oven to 325°F (160°C). Line a 12-cup mini muffin tin with paper liners.
02 - Combine the crushed chocolate sandwich cookies and melted butter in a medium mixing bowl until evenly moistened. Distribute about 1 tablespoon of the mixture into each paper liner and press firmly to create an even base.
03 - Bake the crusts for 5 minutes in the preheated oven. Remove from oven and let cool slightly.
04 - In a large bowl, beat cream cheese and granulated sugar with an electric mixer until smooth. Add the egg, vanilla extract, sour cream, and pinch of salt, mixing just until combined.
05 - Divide the cheesecake filling evenly among the cooled crusts, using about 1 heaping tablespoon for each cup.
06 - Bake for 13 to 15 minutes, until centers are just set but still slightly jiggly.
07 - Allow cheesecakes to cool in the tin for 20 minutes, then transfer to a wire rack. Chill in the refrigerator for at least 45 minutes.
08 - Place the white chocolate in a microwave-safe bowl. Microwave in 20-second intervals, stirring between bursts, until completely smooth.
09 - Spoon or pipe a rounded dollop of melted white chocolate onto each cheesecake to create a ghost shape with a tapered end at the bottom.
10 - While the chocolate is still soft, gently press mini chocolate chips in for eyes and halved regular chips for mouths.
11 - Return cheesecakes to the refrigerator until chocolate decorations have set. Serve chilled.