Pre-heat oven to 180°C (160°C fan-forced). Line 2 oven trays with baking paper.
Place butter and both sugars in the bowl of an electric mixer. Beat until well combined and creamy. Add egg and golden syrup, mixing well.
In another bowl, whisk together the flour, bi-carb soda, baking powder and cinnamon. Add flour mix to the creamed sugar in 2 x batches. Fold in the raisins or sultanas if using.
Roll the mixture into walnut size balls and press flat on the prepared trays, allowing room to spread.
Bake for 15-18 minutes until light golden brown in colour. Cool completely on a wire rack before decorating.
Prepare the royal icing by lightly whisking the egg white with the lemon juice. Gradually add the icing sugar, whisking until well combined and smooth. The icing should be able to hold its shape in order to use for piping. If a firmer consistency is required, gradually add a little more icing sugar.
To decorate, place the royal icing into a piping bag and snip a tiny bit off the end or use a 3mm round tip. Pipe the icing across each biscuit in a criss-cross pattern to simulate bandages on a mummy. Spoon on blobs of jam to simulate blood and decorate with candy eyes.