Start by pouring 3 cups of fresh apple cider into a large pot and bring it to a boil over medium-high heat. Allow it to simmer until it thickens to about 1/3 cup, which should take approximately 30-45 minutes. Let it cool completely.

Preheat your oven to 350°F (175°C).

In a mixing bowl, combine digestive cookies or graham crackers with melted unsalted butter, a pinch of salt, and powdered sugar. Blend until it resembles wet sand. Press into the bottom of a greased springform pan, extending slightly up the sides. Bake for 10 minutes and let cool.

Using a stand mixer, beat the room temperature cream cheese and brown sugar until smooth. Add salt, vanilla extract, and sour cream, mixing well. Gradually pour in reduced apple cider and sprinkle in cinnamon, then add the eggs one at a time while mixing. Blend in flour until just combined.

Pour the filling over the cooled crust. Place the springform pan inside a larger baking dish filled with warm water. Bake for about 90 minutes, until the edges are set and the center jiggles slightly.

After baking, turn off the oven and crack the door. Allow to cool gradually in the oven for about 30 minutes before transferring to room temperature and refrigerating for at least 8 hours.