Among the recipes for traditional, warm & gooey chocolate chip cookies that I've tried, this is my favorite. I used to opt for this one because the dough comes together by hand. But even after acquiring an electric mixer, this is still my favorite. Here are my notes for the recipe.
I make 50g cookies, not 90g. I just like the proportions of a regular-size cookie better than a super-size cookie. With this size, they take 15 minutes on the dot to bake, usually. If I remember, I rotate the pan halfway through.
I've made these using both bittersweet and semisweet chocolate. I prefer bittersweet, but that's just personal preference.
MAKE THE DOUGH AHEAD OF TIME AND LET IT CHILL. We actually made a few cookies only six hours after making the dough, going against the instructions for a 24-hour chill time, and they came out bad. The texture was wrong; brittle and a bit burnt. Then we made another batch at the 48-hour mark, and then another at the four-day mark. The 2-day-out and 4-day-out batches were phenomenal. The cookies really do get better as the dough ages. The internet people who prattle on about the importance of chilling cookie dough are actually right. In the future, always let the dough chill for at least 24 hours. If you can plan ahead enough for a 48 hour+ chill time, all the better.
Let the cookies cool for >10 minutes and <15 minutes so that they're warm and gooey, but not too hot.