Preheat the oven to 200°C / 180°C fan and line 2 baking trays with baking paper.
In a large bowl cream together the butter and sugars until pale and
fluffy, then add the egg and vanilla extract and mix together well.
Sift the flour and salt into the egg mixture, mixing thoroughly until a
soft dough forms. Finally stir in the chocolate chips.
Break off walnut-sized pieces of the dough and roll into balls.
Place these on the baking sheets, leaving space between them.
Bake for 7 minutes for soft chewy cookies, or 10 minutes if you prefer a
crunch. Leave to cool on the trays for about 10 minutes then transfer onto a cooling
rack to cool completely.