In a mixing bowl,add butter,sugar powder,salt beat together using electronic hand beater,beat the mixture until light and fluffy about 3 minutes, add vanilla extract and egg beat to it again, gradually add flour and beat until well incorporated.
Now transfer dough to a pastry bag fitted with nozzle,pipe it like rings/(uyou can do your own design) onto baking tray,spaced 2 inches apart.now bake it 180° for 20 minutes,now Butter cookies is ready and enjoy it after cool completely.