1Start with one and a quarter cup of unsalted butter or 226 grams.
2Add one cup of brown sugar and one quarter cup of granulated sugar.
3Mix the ingredients together.
4Add one egg, one egg yolk, one quarter teaspoon of lemon juice, and two teaspoons of vanilla extract.
5Mix again until combined.
6Add two and three quarter cups of flour, one tablespoon of cornflour, one teaspoon of baking powder, half a teaspoon of bicarbonate of soda, and a pinch of salt.
7Perform one final mix for the cookie dough.
8To make the buttercream, combine 113 grams of butter (or one stick), one and a half cups of icing sugar, one quarter cup of brown sugar, one teaspoon of cinnamon, two teaspoons of vanilla extract, and two tablespoons of double cream.