Prepare the Crust:

• Grease a 5cm-deep, 20cm x 26cm roasting pan and line with baking paper, allowing the paper to overhang the long sides.

• Place the coarsely chopped biscuits into a food processor and process until they resemble fine crumbs.

• Add the melted butter to the biscuit crumbs and process until well combined.

• Transfer two-thirds of the mixture to the prepared pan. Use a flat-bottomed glass to press the mixture evenly over the base. Refrigerate for 30 minutes to chill.

• Reserve the remaining crumb mixture for topping.

Prepare the Salted Caramel Layer:

• In a saucepan over medium heat, combine the sweetened condensed milk, golden syrup, and salted butter. Cook, stirring continuously, until the mixture comes to a boil and thickens slightly.

• Stir through the sea salt flakes.

• Pour the caramel over the chilled biscuit base, spreading it evenly. Refrigerate for about 30 minutes until set.

Prepare the Filling:

• Using electric beaters, beat the room-temperature cream cheese, icing sugar mixture, and vanilla extract in a large bowl until pale and creamy.

• Gently fold the whipped cream into the cream cheese mixture until just combined.

• Spoon the filling over the set caramel layer, smoothing the top with a spatula.

Assemble and Chill:

• Sprinkle the reserved biscuit crumb mixture over the top of the filling.

• Refrigerate the cheesecake for at least 4 hours or overnight to set completely.

Serve:

• Once set, use the overhanging baking paper to lift the cheesecake from the pan.

• Place on a serving board and slice into 16 pieces.

• Sprinkle with additional sea salt flakes before serving, if desired.