Preheat the oven to 190 degrees Celsius. Beat the butter on low for 30 seconds then increase to medium and gradually add in sugar and beat till creamy, total 6 minutes. Beat in egg, orange zest and vanilla essence.
Sift together the dry ingredients. Stir the dry ingredients and chocolate chips into the butter mixture and combine.
Scoop the batter by tablespoonfuls (or roll into balls and flatten) onto a non-stick baking sheet 5 centimetres (2 inches) apart. Bake for 8 to 10 minutes. Cool for five minutes on baking sheet then transfer the cookies onto a rack to cool completely.
Store cooled cookies in an airtight container for up to four to five days.