Preheat your oven to 325°F (160°C). Line a 9-inch springform pan with parchment paper and grease the sides lightly.

In a food processor, blend digestive biscuits (or graham crackers) with cinnamon and sugar until fine. Melt the butter and combine with crumbs. Press mixture into springform pan and bake for 10 minutes.

Mix dark brown sugar and cinnamon in a small bowl for the topping. Set aside.

Stir together all-purpose flour and brown sugar mixture in a bowl. Add melted butter and mix until coarse crumbs form.

Beat cream cheese until smooth. Gradually add sugar, sour cream and cornstarch. Beat in eggs one at a time, mixing until just combined.

Pour half the cheesecake batter over the cooled crust, sprinkle with cinnamon sugar, then add remaining batter and top with crumble mixture.

Prepare a water bath by placing the springform pan in a larger baking dish with hot water. Bake for 1 hour and 15-20 minutes until edges are set.

Turn off the oven and leave the cheesecake inside with the door ajar for an hour. Chill in the fridge for at least 6 hours or overnight.