On low speed, cream butter until no lumps remain.
Add sugar and beat on medium speed for 3-4 minutes or until the mixture becomes pale and fluffy.
Add vanilla and mix till well blended.
Sift in flour, cornflour, baking powder, and salt. Combine till dry ingredients are invisible.
Add milk in two installments and combine with fingers to form a dough.
Wrap the dough with a cling wrap. Freeze for 30 minutes/ Chill for 1 hour.
In a small bowl mix brown sugar and cinnamon till there are no lumps. Set aside.
Break the dough in to a bowl and work with hands till it becomes smooth.
Place parchment/butter paper on a rolling surface. Place the dough and again place a parchment paper on top.
Roll the dough into a rectangular sheet with 1/2 to 1 cm thickness.
Spread softened butter on the sheet evenly.
Spread the brown sugar and cinnamon mix evenly.
Roll the dough tightly into a log. Divide the roll into two.
Wrap each roll individually with a cling wrap and refrigerate for 2 hours/freeze for 1 hour.
Preheat the oven to 180℃/350℉.
Cut the roll into thin slices of around 1/2 cm thickness.
Place them on a parchment/butter paper lined baking tray with little distance between them.
Bake them in the preheated oven at 180℃/350℉ for 10-12 minutes or until they achieve a golden brown colour.
Remove the cookies from the tray after 10 minutes and place them on a wire rack to cool completely. Store in an airtight container.