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.
Notes
The two sizes of ramekins I used in the photos that you see in this post (and in the recipe) were 8cm and 9cm diameter (inside measurement) or 3 ¼ inch and 3 ½ inch respectively. Both sizes were approximately 5 ½cm high/tall (again inside measurement) or 2 ¼ inches. My reasoning for this was to experiment with the different sizes and see if this altered my end product significantly - which it didn't. The larger diameter ramekins were only slightly less cooked than the smaller ones, but it didn't make a big difference. You could take out the smaller ramekins when you were happy and just leave the others in for 2 mins more if you wanted to. As far as ramekin height goes, I wouldn't go under 4 ½cm or 1 ¾ inches.**Long story short - if you don't have enough matching ramekins it doesn't matter too much - besides mismatched and eclectic is in fashion!**Update on ramekin size - since I have now actually tried to shop for ramekins online I realise that capacity is a more relevant unit of measurement! Sorry! The smaller ramekins I used were 1 cup / 8 oz capacity, up to the largest being about 1 ¼ cup / 10 oz.The reason I use a high-sided bowl in step 3 is because the butter & sugar can tend to escape the bowl a bit - depending on the softness of your butter and the lowest speed of your mixer (mine is pretty high! hence the high sides).I actually weighed the amount of raw dough then divided by 4, so I could measure out the exact equal portions into each ramekin. I weigh a lot of things like this, I find it helps me get a more consistent outcome. There is also no need to get too particular when smoothing the tops, they will smooth out in the oven. I find the back of a teaspoon dipped in water works just fine - the same as using wet hands to ball up cookie dough or meatballs.*Please note that the amount of calories per serve is provided as a guide only, as ingredients and cooking methods can vary greatly*