Holly Christmas biscuits

This is such an easy recipe, but I like the holly decoration on the top. It's a bit fiddly to do, but I think they look Christmassy and a bit different from other Christmas biscuits. The basic biscuit recipe is one I've had for years, and I saw the holly and berries idea in a baker's shop window. I went in and bought some bread and asked about the holly biscuits and the kind lady explained how they were done. So easy, and adaptable to other designs and cutters.
The recipe makes about 12 biscuits.

75g butter
50g icing sugar
grated rind of a lemon
1 egg yolk
175g plain flour
pinch of salt

Decoration:
2 egg yolks
red and green food colouring

Preheat oven 190C/375F/gas5

Lightly grease 2 baking trays.

Beat the butter, sugar and zest together till fluffy; beat in the egg yolk and add the flour and salt. Mix to a smooth dough. Wrap in clingfilm and put in the fridge for about half and hour.

Roll the dough out on a floured surface to about 3mm thick, then using a 6cm cutter cut out round shapes. A good tip is to flour the cutter so it doesn't stick.

Put the biscuits onto the baking trays.
Mark the tops of the biscuits lightly with a 21/2 cm holly leaf cutter for the leaves and the tip of a 5mm plain piping nozzle for the berries. Chill again for about 10 mins till the biscuits are firm.
For the decoration - using 2 egg cups, put an egg yolk in each one and mix red colouring into one cup and green into the other. Using a small paint brush, paint the colours on the leaves and berries.

Bake for 10 - 12 mins till the biscuits start to colour round the edges.

Cool for a bit on the tray and then finish off on a wire rack.