Beat sugar and butter in a large bowl with an electric mixer until light and fluffy. Beat in eggs, egg yolk, green food coloring and peppermint essence until smooth.
Combine flour, baking powder, bicarb, cream of tartar, and salt in a separate bowl. Mix into egg mixture until dough comes together. Fold in chocolate chips. Cover dough and refrigerate until firm enough to scoop, about 1 hour.
Preheat oven to 175 degrees C. Line 2 baking trays with baking paper.
Drop spoonfuls of dough 5cm apart onto the baking trays.
Bake in the preheated oven until edges are golden, 8 to 10 minutes. Cool on the baking tray for 1 minute before removing to a wire rack to cool completely.