Mix sugar and melted butter, then yolk, vanilla and salt. Mix in dry, then choc chips. Shape into 2 x 1.5cm/0.6" thick discs. Bake 13 - 14 min at 190°C/375°F (170°C fan-forced).

Preheat oven to 190°C/375°F (170°C fan-forced). Place a sheet of baking paper on a tray.

Partially melt butter - Put the butter in a microwave proof bowl. Heat on high for 30 seconds or until mostly melted. Stir to finish melting - it should look a little milky. (Note 3)

Wet ingredients - Add both sugars into the butter, mix with a rubber spatula to combine. Add yolk, vanilla and salt. Mix to combine.

Dry ingredients - Scatter flour across surface then baking soda across flour. Mix until flour is almost fully incorporated. Mix through most of the chocolate chips (reserve some for topping).

Shape - Form 2 balls and flatten to 1.5cm/0.6" thick. Place on tray. If your dough is too sticky to handle, pop it in the fridge for 5 to 10 minutes (see Note 4).

Smaller/larger cookies - You can also do 3 or 4 smaller cookies (same bake time and temp) or one giant cookie (see below).

Bake for 13 - 14 minutes or until edges are tinged gold and the centre is pale golden.

Top - Place reserved chocolate chips on top of each (chocolate will melt and glue to surface) and sprinkle with salt flakes if using.

Cool 10 minutes - Leave cookies to cool on the tray for 10 minutes so they firm up and finish cooking. Then attack! (Or transfer to rack to fully cool then store in an airtight container).

Preheat oven to 180°C/350°F (160°C fan-forced). Make one large ball and flatten to 2cm/0.8" thick. Bake 16 - 18 minutes until edges are golden and middle is pale golden. Press reserved chocolate chips on surface, cool 10 minutes on the tray before attacking!