You will need 4 ramekins approximately 8cm (3 ¼ inches) in diameter (see notes).
Pre heat oven to 180c.
Combine the sugar & butter in a high-sided bowl (see notes).
Using a hand-held electric mixer, beat until light & creamy, 3 - 4 mins.
Add egg & vanilla, again beating to incorporate.
Sift over plain/all-purpose flour & bicarbonate of soda, then mix until combined.
Fold in chocolate chips.
Divide mixture evenly between ramekins, smooth tops with the back of wet teaspoon (see note).
Bake for 13 - 15 mins - depending on your desired level of goo vs cookie ratio.
Allow to cool for 5 - 10 mins before serving.