Chocolate chip cookies

In a large bowl, whisk together the flour, baking powder, bicarbonate of soda and sea salt flakes, set aside.

Put the butter in a second bowl with both sugars. Mix together to combine (don't worry if the moxture looks separated at this stage). Add the egg and yolk, then whisk until the mixture is smooth and fully combined. Tip in the flour mixture and stir to form a soft cookie dough. Add the chocolate and mix briefly just until evenly distributed (don't worry if the dough seems quite loose). Cover and chill for 1-2 hours to firm up.

Line 2 baking trays with baking parchment. Divide the dough into 10 even-sized portions and roll into balls. Put the balls on the prepared trays and chill for 1 hour (if you haven't much fridge space, put them all in 1 baking tray in the fridge, then spread them out between 2 trays after chilling).

When ready to bake, preheat the oven to 180°C, gas mark 4. Sprinkle each cookie with some extra sea salt flakes. Bake for 15-16 minutes or until the cookies are golden around the outside but still a touch paler in the centre. Remove and set aside to cool on the trays for about 10 minutes, then transfer to a cooling rack.