Preheat oven to 180 degrees C. Line a baking tray with baking paper.
Sift together flour, baking powder, salt and orange zest.
In a mixer bowl cream butter on medium speed, adding sugar gradually. Add vanilla and egg. Add flour mixture gradually, stopping frequently to push down from sides of bowl. When flour mixture is thoroughly combined, mix in chocolate chips.
Drop dough by scant spoonful onto baking tray, spacing 3cm apart, flattening slightly with back of spoon. Bake 10 to 12 minutes or until beginning to brown. Allow to cool completely on cooling rack.