For the cookies
7 oz. unsalted butter, room temperature
10 oz. caster sugar
1 tsp. vanilla extract
1 egg
¼ tsp. salt
16 oz. plain flour, plus extra
1 tsp. cream of tartar

For the royal icing
2 egg whites
16 oz. icing sugar, sifted plus extra
1 tsp. glycerine (optional)
Food colouring (optional)

1. In a large mixing bowl, cream together the butter and sugar for 5 minutes or until pale and fluffy. Add the vanilla and egg and mix until fully incorporated. 
2. Add the salt, then sift in together 13 oz. flour and cream of tartar. Rub the mixture together with your fingertips until it resembles fine crumbs. Add more flour if necessary until it starts to come together to form a dough.
3. Gently tip over the mixture onto a surface lined with clingfilm. Bring any remaining crumbs together until you forms a ball, but do not knead it – it will be a slightly crumbly dough but that’s ok. Divide into two equal pieces and flatten into thick discs. Wrap them each in clingfilm and leave in the fridge for 15 minutes. 
4. Preheat oven to 170º Celsius and line three cookie sheets with baking paper. 
5. Turn one of the dough discs on to a lightly floured surface and roll until it until a ¼ inch thick. Use your cookie cutters to cut out shapes and then place on to the cookies sheets about ½ inch apart. 
6. Re-roll the dough and continue to cut out shapes. (Repeat this process with the remaining dough until there is none left). 
7. Place the cookies in the fridge for 10 minutes. 
8. Bake in the oven for 10-15 minutes. The cookies should be golden brown around the edges but pale in the center. (If your oven is not an even temperature, bake them one batch at a time in the middle of the oven.) 
9. Once bakes, place the cookie sheets on a wired rack to cool completely. 
10. For the royal icing, whisk the egg whites until frothy. Next, add the icing sugar and glycerine. Mix thoroughly until you have a smooth consistency. The mixture shouldn’t be runny or stiff. It should be able to coat the back of a spoon. If it’s too thick add water; if it’s too runny add more icing sugar. Stir in a few drops of food colouring if using. 
11. Add a couple of tablespoons of the icing in a piping bag fitted with a small writing nozzle. Pipe the outline of all the cooled cookies and then use another piping bag fitted with a slightly larger nozzle to fill with remaining icing. Decorate as desired. (An alternative method to ice the cookies is to dip them flat side down). 
12. Leave to dry for up to 2-5 hours. Enjoy!