Preheat oven to 325°F (160°C). Line a 12-cup muffin tin with paper liners.

Mix crushed Oreos with melted butter; press about 1 tbsp into each liner to form crust.

Beat cream cheese and sugar until smooth, then add egg, vanilla, sour cream, and salt; mix until combined.

Spoon cheesecake batter over crusts, filling each about 3/4 full. Top with a small Oreo half if desired.

Bake 15–18 minutes until edges set but centers jiggle slightly. Cool 30 minutes, then refrigerate at least 2 hours.