• Blend the flours, salt and bicarbonate of soda in a bowl. Set aside.
Place the sugar, treacle and golden syrup in a small saucepan over a very low heat to dissolve the sugar. Take care not to let the mixture boil or caramelise. Remove from the heat, add the butter and spices, and stir vigorously to incorporate the butter into the mixture. Pour into a large bowl and leave to cool for 5–8 minutes.
• In a small bowl, whisk together the psyllium husk and water, then add this to the spiced butter mixture and stir. Set aside to cool for 10 minutes.
Add the egg to the spiced butter mixture and stir, followed by the flour mixture. Stir with a spoon, then work the dough together with your hands for a minute or two. The dough will be quite loose.
• Wrap the dough in clingfilm or place it in a plastic bag. Refrigerate and leave it to rest until the next day.
• Lightly flour the work surface with potato starch or rice flour. Roll the dough out in batches. Initially, it will appear crumbly, but persevere—it will come together.
Use a cookie cutter to stamp out the biscuits, then place them on baking trays lined with parchment paper.
• Bake in the middle of a preheated oven at 190°C (fan) for approximately 5–7 minutes, depending on the size of the biscuits. They will harden as they cool.

To decorate

• Mix royal icing with a little water to a pipe-able consistency.