Start by creaming together your sugar and butter in a large mixing bowl until fluffy and pale. Make sure everything is combined.
Crack the egg into the bowl and add the vanilla essence. Beat until combined.
Add the flour and beat until the dough comes together.
Put a sprinkle of extra flour onto a work surface and tip the dough out. Need gently until it all comes together and forms one ball (then stop - you don’t want to overwork the dough).
Cut the dough into two equal pieces and wrap each one in clingfilm. Put in the fridge and allow to chill for an hour.
Meanwhile, preheat the oven to 180 degrees Celsius.
After an hour, prepare two baking sheets by lining them with baking parchment.
Remove the biscuit dough from the fridge. Dust the work surface with more flour and tip one half of the dough out onto it. Using a rolling pin, roll until it is 3-4mm thick.
Use your ‘base’ cookie cutter to cut twelve pieces from the dough. Place them evenly on one of the baking sheets.
Next, roll out the second half. Use your ‘top’ cookie cutters (with the shape in middle) to cut another 12 pieces. Place these evenly on the other baking sheet.
Put both baking sheets in the oven. Bake for 10 minutes, checking often - they might cook more quickly depending on your oven type. They are done when they are hardened and very lightly golden. If they are still soft after 10 minutes, leave them for a couple more minutes.
Remove from the oven and leave to cool completely on a wire rack.
When cool, compile by putting half a teaspoon of jam on a ‘base’ cookie. Spread evenly with a knife, then top with a ‘top’ cookie. Continue until all are sandwiched.