• Add the butter and caster sugar to a large mixing bowl. Using an electric mixer (or wooden spoon) beat together until pale and creamy. Add the egg and almond extract and beat together until combined. 
• Add the flour and mixed spice and using a spoon - and then your hands - bring the dough together. It may be a bit sticky but that's fine at this stage. Wrap it in cling film and chill in the fridge for at least 45 minutes.
• Preheat the oven to 180C / Fan 160C / Gas Mark 4 and line two baking trays with baking paper.
• Remove the dough from the fridge, dust with a little extra gluten free flour and roll out to around 3mm thickness. Using an egg-shaped cutter, cut out 48 egg shapes. You might need to re-roll the dough a few times to get them all. 
• Place the eggs on a baking sheet, and use a small circular cutter (or large piping nozzle) to cut a 'yolk' hole out of half of them.
• Bake in the oven for approximately 10-12 minutes until golden. Remove from the oven and transfer to a cooling rack for them to cool completely.

To decorate the biscuits:

• Mix the icing sugar and milk together into a smooth paste. Dip all of the egg biscuits with a hole into the icing, to form a layer on top. Leave on a cooling rack to firm up.
• Spread the other half of the biscuits (with no holes) with a layer of jam. Carefully sandwich the two pieces together so the icing is on top and the jam pokes through the hole to form a 'yolk'.