Preheat the oven to 220°C and line a baking tray with parchment.
Rub the flour and butter together until the mixture resembles breadcrumbs, then stir in caster sugar.
Mix in the cream one tablespoon at a time until a soft dough forms.
Combine the grated apple, cinnamon, and one teaspoon of demerara sugar in a separate bowl.
Roll the dough on a floured surface into a rectangle about 0.5cm thick.
Spread the apple mixture over the pastry using a slotted spoon to omit excess juice.
Roll the pastry tightly from the long side and cut into seven thick slices.
Place swirls on the tray, sprinkle with remaining sugar, and bake for 20-25 minutes until golden.