1. Preheat oven to 160ºC (325ºF). In a food processor, blend digestive or graham crackers, dark brown sugar, ground cinnamon, and nutmeg until fine and sand-like. Add melted butter and blend to combine.
2. Line bottom of a 22 cm springform pan with parchment paper. Press cookie mixture firmly into bottom and up sides. Bake 10 minutes, then cool.
3. Dice apples and toss with granulated sugar and cinnamon; set aside without liquid.
4. Mix all-purpose flour, dark brown sugar, and cold butter by hand or mixer until crumbly; set aside.
5. In a mixer, beat cream cheese on low for 1 minute. Gradually add granulated sugar, continue mixing on low for 1 minute.
6. Whisk sour cream and cornstarch smooth, add with vanilla to cream cheese mixture, mix low until combined.
7. Add eggs one at a time, mixing gently until incorporated. Scrape bowl and mix once more.
8. Pour batter into prepared pan. Evenly distribute apple mixture on top, then sprinkle crumble over apples.
9. Bring water to boil in kettle. Place springform pan inside 25 cm cake pan, then into larger roasting pan. Pour hot water until about two-thirds up cake pan, creating water bath. Optionally, wrap springform pan in 3 foil layers to prevent leaks.
10. Bake cheesecake 1 hour 20-30 minutes until center slightly wobbly. Turn off oven; leave door slightly open, cool 1 hour inside oven.
11. Remove from water bath, peel off foil if used. Cool completely at room temp about 1 hour.
12. Refrigerate at least 6 hours or overnight to fully set.