These melt-in-the-mouth shortbread biscuits are sandwiched with tangy apple jam and topped with crisp apple slices.
Preheat the oven to 180°C/160°C fan/350°F/Gas 4. Start the biscuits by placing the 2 whole large eggs in a small pan of boiling water. Boil for 10 minutes, until the eggs are hard boiled. Gently drain the eggs, then run them under cold water to stop them cooking. Set aside to cool.
Make the jam. Place the Bramley apple pieces in a medium pan. Pour in the apple cider and add 50ml of water. Add all the other jam ingredients, except the sugar. Bring to the boil over a high heat, then reduce the heat to low and simmer for 10 minutes, until the apples are tender.
Leaving the pan on the heat, crush the apples with a potato masher. Add the sugar and cook on a medium heat for 30–35 minutes, stirring occasionally, until the mixture is thick and reaches 105°C/221°F or the jam-setting point on a sugar thermometer. Pour into a shallow dish and spread out to cool completely. Remove and discard the cinnamon stick.
To make the caramelised cider apples, combine all the ingredients in a pan, place over a high heat and bring to the boil. Lower the heat and simmer for 20–25 minutes. Remove from the heat and transfer the apple slices to a lined baking sheet. Discard the syrup. Place the apple slices in the oven for 15–20 minutes, until browned. Set aside to cool.
Meanwhile, make the biscuit dough. Cream the butter and sugar in a mixing bowl until pale and fluffy. Peel the hard-boiled eggs and push the boiled egg yolks through a sieve into the bowl (discard the egg white). Stir in the raw egg yolks and vanilla extract. Beat the mixture until combined, then beat in the flour, salt and cinnamon until it forms a stiff dough. Wrap the dough in cling film and freeze for 15 minutes to chill quickly, until firm enough to roll out.
Roll out the dough on a lightly floured work surface to 5mm thick. Use the cutter to cut 48 discs, re-rolling the trimmings as necessary. Place the discs slightly apart on the lined baking sheets and bake for 12–14 minutes, or until golden brown. Transfer to a wire rack to cool.
To assemble the biscuits, turn half of the biscuits bottom upwards and spread 1 heaped teaspoon of jam on each. Sandwich the jam with the other 24 biscuits, bottom downwards. (Store the remaining jam in the fridge for another time.)
Make the icing. Sift the icing sugar into a bowl and stir in the milk to give a thick pouring consistency. Place a teaspoonful on top of each biscuit.
Place 8 of the cooled, baked apple slices in a blender and blitz to create a fine dust. Sprinkle the dust over each biscuit and top with a whole slice of baked apple.