Preheat oven to 180C / 350F (standard) or 160C/320F (fan / convection). Place oven shelf in the middle of the oven.

Line 2 trays with baking / parchment paper.

Whisk the flour, salt and baking soda in a bowl.

Place the butter in a large heatproof bowl. Microwave until the butter is almost fully melted (25 sec for room temp butter, 40 sec for fridge cold butter on high).

Whisk to finish melting the butter. (Note 2)

Add brown and white sugar, whisk energetically for 15 seconds.

Add egg, yolk and vanilla, whisk well for 15 seconds.

Add flour mixture and mix until flour is almost fully incorporated.

Add 1 cup chocolate chips, stir to disperse and flour is fully incorporated. Batter will be quite loose.

Stand for 5 minutes for batter to firm up a bit so it is scoop-able into mounds. (Note 3)

LARGE COOKIES: Scoop up a level ice cream scoop / 3 tbsp / 1/4 cup (Note 4) and place on baking trays 5cm / 2" apart - 13 balls. Top with remaining choc chips (these remain on surface once baked = prettier).

SMALL COOKIES (26 - 30): Scoop up 1.5 tbsp (heaped tbsp measure) OR 1/2 an ice cream scoop (this works well). Place on baking trays 4cm / 1.75" apart, top with choc chops.

Bake 1 tray at a time. LARGE COOKIES: Bake for 8 minutes, then rotate the tray and bake for 3 minutes (11 minutes in total). SMALL COOKIES: Bake 6 minutes, turn then bake 3 minutes (9 min total). The cookies should be just golden on the edges and pale golden on top. They will be slightly puffed up.

Cool on the tray - they finish cooking. They will lose the puffiness while resting. Dig in and get your cookie fix!