Step 1: Reduce the Cider. Begin by pouring 3 cups of fresh apple cider into a saucepan. Bring it to a boil over medium-high heat, optionally adding mulling spices for enhanced flavor. Allow the cider to simmer, reducing to about 1/3 cup, which should take around 15-20 minutes. You'll know it’s ready when it's fragrant and has thickened slightly. Set the reduced cider aside to cool.

Step 2: Prepare the Crust. Crush your digestive cookies or graham crackers into fine crumbs using a food processor or a zip-top bag with a rolling pin. In a mixing bowl, combine the crumbs with melted butter, a pinch of salt, and powdered sugar, mixing well. Press this mixture evenly into the bottom of a greased and lined 9-inch springform pan. Bake at 350°F for 10 minutes, then remove it from the oven to cool.

Step 3: Mix the Filling. In a large mixing bowl, beat the softened cream cheese and brown sugar together until smooth and creamy. Next, add in the sour cream, vanilla extract, ground cinnamon, and cooled reduced apple cider, mixing thoroughly until well combined. Gradually add eggs one at a time, gently mixing after each addition to avoid incorporating too much air.

Step 4: Add the Flour. Once the egg mixture is smooth, gently fold in the all-purpose flour just until combined. Be careful not to overmix, as this can lead to a dense cheesecake.

Step 5: Bake the Cheesecake. Pour the filling evenly into your cooled crust, smoothing the top with a spatula. To prevent cracking, place the springform pan in a larger baking dish filled with hot water, creating a water bath. Bake at 325°F for about 90 minutes. The edges should be set, while the center has a slight jiggle when shaken gently.

Step 6: Cool the Cheesecake. Once the baking time is up, turn off the oven and crack the door open slightly. Allow the cheesecake to cool in the oven for 30 minutes, which helps prevent sinking. Afterward, carefully remove it from the water bath and refrigerate for a minimum of 8 hours or overnight.