Preheat the oven to 190 °C. Line two baking trays with non-stick baking paper.
Place the butter, brown sugar and white sugar into a bowl. Beat until creamy. Beat in the vanilla extract and egg. Sieve the flour and bicarbonate of soda in a bowl. Mix with a wooden spoon. Stir dry ingredients to wet ingredients. Do not over mix. Fold in the chocolate chips.
Scoop the mixture with a teaspoon and drop onto the prepared baking sheet, space about 1 1/2 inches apart. Bake in the oven for 8 mins until light brown on the edges and still slightly soft in the center.
Leave cookies on the tray for a couple of minutes to firm up then transfer to a cooling rack.