Heat oven to 180C/160C fan/gas 4 and
line 2 large baking sheets with baking
parchment. Put the butter, sugar, egg
yolk, vanilla and ¼ tsp salt into a large
bowl and beat with a wooden spoon until
smooth. Stir in the flour to make a stiff
dough, then shape into 2 discs, cover
with cling film and chill for 10 mins.
With plenty of extra flour on the work
surface and rolling pin, roll a batch of
dough to the thickness of a £1 coin.
Stamp out as many 7cm rounds as you
can. In half of the rounds, stamp out 2 eye
sockets with an apple corer, then use
well-floured fingers to pinch the jaw
shapes. Lift onto the baking sheets. Bake
for 15 mins or until pale golden, then cool
for 2 mins before lifting onto a wire rack.
Sandwich the cold biscuits together
with the jam. Mix the icing sugar with
4 tsp water until smooth, divide into 3,
then colour as you like. Put into piping
bags, snip off the tips, then pipe spooky
patterns and faces onto the skulls.