Butter and line a 20cm loose-bottomed tin with baking parchment. Blitz the biscuits in a food processor with the cinnamon, then pour in the melted butter. Mix well to coat all the biscuit crumbs, then press into the lined tin to create an even base. Put in the fridge to set for about 1 hr.

To make the cream cheese filling, beat the cream cheese with the icing sugar and vanilla until light, then add the double cream and beat until well mixed and thickened. Spoon this onto the biscuit base, smoothing across the surface and ensuring no air bubbles remain. Smooth with the back of a spoon or spatula and put in the fridge to set for 3 hrs.

For the topping, beat the sweet potato, cream and mixed spice together until thickened. Carefully spoon this onto the cream cheese layer, once again using the back of a spoon or a spatula to smooth across the surface and ensure no air bubbles remain. Leave to set in the fridge overnight. Drizzle over the maple syrup, then sprinkle with the caramel popcorn and a pinch of sea salt.