A simple butter cookie

A simple taste yet really nice, my mission of butter cookie is to bake as good as the expensive blue tin butter cookies, which I don really remember the name,brand or company, just recognize the blue tin. I haven't got the best one yet, but this is reliable

Ingredient:

175g    Unsalted Butter/margarine
90g      Golden Caster Sugar
250g    Plain Flour
optional: Demerara(Raw) sugar for coating

• Beat butter and sugar until light and fluffy
• Add flour and beat until mixture foams a smooth dough
• Roll as in sausage, cylinder or any shape 
• sprinkle above or coat all around it with demerara sugar 
• wrap it with plastic wrap and chill for 30minutes or next day
• cut it into thick slices and place on baking sheet
• bake it at 160'C for 20minutes
• Let it cool and it will harden eventually