1. Boil the cider with mulling spices for 1 hour until reduced to 1/3 cup. Cool.
2. Preheat oven to 350°F.
3. Pulse cookies in a food processor until ground. Add butter, salt, and sugar; pulse to combine.
4. Press crust mixture into a springform pan and bake.
5. Beat cream cheese and sugar until smooth. Add sour cream, vanilla, salt, cinnamon, and cider; mix until creamy.
6. Add eggs and flour; beat until just combined.
7. Pour filling into crust. Bake for 90 minutes until set but wobbly in the center.
8. Cool in the oven with the door ajar, then refrigerate for 8 hours before serving.