Boil the fresh apple cider with mulling spices on high heat for about an hour until it thickens into a syrupy consistency.
Preheat your oven to 350°F (175°C).
Pulse the digestive cookies or graham crackers until finely ground, then mix with melted butter, salt, and powdered sugar. Press into a springform pan and bake for about 10 minutes.
Lower the oven temperature to 325°F (160°C). Beat the softened cream cheese and brown sugar together until smooth.
Add in sour cream, pure vanilla extract, salt, cinnamon, and the reduced apple cider mixture. Mix until velvety.
Gently add in eggs one at a time followed by the flour. Beat just until incorporated.
Place the springform pan into a larger pan filled with hot water. Pour the filling over the crust and bake for about 90 minutes until set around the edges.