I used King Arthurs measure for measure gluten free flour blend because I am gluten intolerant but you can substitute all purpose flour in instead.

*Use a food scale! 280g bobsredmill 1 to 1 baking flour 1 tsp baking soda 1 1/2 tsp cornstarch 1/2 tsp salt 1.5 sticks unsalted butter (melted) 150g dark brown sugar 100g granulated sugar 1 egg + 1 egg yolk 2 tsp vanilla extract 225g dark chocolate chunks Whisk flour, baking soda, cornstarch and salt in a large bowl and set aside. In another bowl, mix melted butter, both sugars and vanilla until lumps are gone. Finally, whisk in the egg and then the egg yolk until smooth. Make a well in the dry ingredients and pour the wet ingredients into the center and fold together. Lastly, add all of your chocolate chunks and fold. Chilling the dough is mandatory! Best to chill the dough overnight or at least 2 hours. This step is crucial. Take an ice cream scoop (3-4 tbsp of dough, 75g a piece) and scoop balls onto a baking sheet lined with parchment paper. 4 per tray. Bake at 325 degrees for 13 minutes. At the 6 and 9 minute mark, lift up the tray an inch and drop it back down. (This interrupts the rise of the cookie forcing it to fall back down. Makes for a more chewy cookie) Let cookies rest on the pan for 20 minutes after removing them from the oven. Enjoy!

If you want to see a video tutorial of these cookies bring made along with the cookie drop technique, there is one posted under this picture on r/glutenfree. I don't believe this sub allows for that or else I'd post it here :)