Chocolate chip cookies

Method

1. Beat the butter and both sugars with an electric mixer on medium-high for 2 to 3 minutes, until lighter in colour and fluffy (or with a wooden spoon, beating hard for about 5 minutes). The air you beat in now gives the cookies a tender centre.
2. Beat in the eggs one at a time on medium, letting each one disappear before you add the next, then beat in the vanilla. Scrape down the sides of the bowl so all the butter is mixed in and the cookies bake evenly.
3. Mix the flour, baking soda and salt in another bowl, add them to the butter mixture and mix on low only until no dry flour is left. Fold in the chocolate with a spatula.
4. Roll the dough into 20 balls, about 60g each, and set them on four sheets of baking paper, five to a sheet and 8cm apart. Lay the sheets on trays or boards (stack them if you need to), cover and chill for at least 1 hour, or up to 3 days, so they bake up thicker and more flavourful.
5. About 15 minutes before the chill is up, heat the oven to 180°C (160°C fan) with shelves in the upper and lower thirds. Slide two sheets of chilled balls onto two trays and keep the rest in the fridge.
6. Bake both trays for 12 to 14 minutes, swapping them top to bottom halfway, until the edges turn golden and set but the centres still look pale and soft.
7. Scatter a few salt flakes over each cookie straight away. Leave them on the trays for 5 minutes to firm up, then slide the paper onto a rack so the trays are free for the second round.
8. Once the trays are cool enough to touch, slide on the last two sheets and bake them the same way, 12 to 14 minutes, then salt and cool as before. Serve warm or at room temperature with a glass of cold milk; they keep in a tin for 3 days.