To make the biscuits, mix together the butter and sugar in a bowl with a wooden spoon until well combined. Add the egg and vanilla, and continue to beat by hand until fully incorporated. You will need to scrape down the edges of the bowl for this part.

Tip the flour into the mixture and fold together until fully combined. Shape the dough into a ball and then gently flatten it into a disc for easier handling. Put the disc of dough onto a floured sheet of baking parchment. Ensure the dough has an even thickness of around 5mm. Once shaped, carefully transfer the entire sheet of parchment with the flattened dough to a baking tray. Pop the tray into the fridge for 10 mins to allow the dough to firm up.

Remove from the fridge and press out your biscuits using a 6cm flower-shaped cutter (you could use any shaped cutters to make these). You will need 16 biscuit bases and 16 biscuit tops, with small holes or flowers of around 3cm cut out of the tops.

Recombine the dough off-cuts and reroll them on a floured surface. Try to be fairly quick doing this otherwise the mixture will warm up and get sticky. If it does, just put it back in the fridge to firm up again.

Once the shapes are cut out, arrange on 2 baking sheets lined with baking parchment and leave to cool in the fridge for 10 mins.

Heat the oven to 190C/170C fan/gas 5. Bake the biscuits for 7 mins, then take them out of the oven and sprinkle the tops with caster sugar. Return all the biscuits to the oven and cook for a further 5 mins. Take out and allow to cool fully on a wire rack. When cool, spread jam on the bottom biscuits and cover with the top biscuits, sandwiching them together. Will keep for 2-3 days in an airtight container.