Preheat the oven to 180°C and line a baking tray with cooking paper.
Beat the butter and all the sugars together.
Beat in the egg and vanilla essence.
Crush the biscuits either by hand or in a food processor.
Add the dry ingredients to the wet and beat on a low speed until all combined into a sticky dough.
Roll into balls and place on the tray, making sure ou leave space between each ball as they will spread a little.
Refrigerate for at least ¾ of an hour.
Bake for 10-12 minutes. They will be soft.
While you wait for the cookies cool make the icing.
Place the icing sugar and butter in a bowl.
Add the lemon juice and 1 teaspoon of boiling water. Mix until it is a thick but pipeable consistency. Add more water as needed.
Line the cookies up and place the icing in a piping bag with a thin tip and pipe in a straight line over all the cookies. Turn the cookies 90° and repeat.
Notes
Leave some of the crushed biscuits larger than others for more crunchy bits. If you just want a softer texture, crush them smaller. If you want less spreading, chill the dough for at least 2-3 hours. Test the dough when putting in the spices. You may want more or less depending on you personal taste. Omit the lemon juice in the icing if you just want plain icing.