Preheat your oven to 160ºC (325ºF) and line the bottom of a 9-inch springform pan with parchment paper.

In a food processor, combine the digestive or graham crackers, dark brown sugar, ground cinnamon, and nutmeg. Pulse until fine crumbs. Add melted butter and blend until resembling wet sand. Firmly press into the bottom and slightly up the sides of the springform pan, then bake for about 10 minutes and allow to cool.

Dice apples and toss with granulated sugar and a bit of cinnamon. Set aside.

In a bowl, combine all-purpose flour, dark brown sugar, and softened butter. Rub together to form a crumbly mixture.

Beat softened cream cheese until smooth; add granulated sugar and mix well. Combine sour cream and cornstarch, then mix into the cream cheese along with vanilla extract. Add eggs one at a time, mixing gently.

Pour cheesecake filling into the cooled crust, layer with apple filling, and sprinkle the crumble topping over the apples.

Bake in a water bath for 1 hour and 20-30 minutes until slightly wobbly but edges are set. Let cool in the oven for about an hour.

Remove from water bath and refrigerate for at least 6 hours or overnight.