Step 1

Preheat the oven to 180C/160C Fan/Gas Line a baking sheet with baking parchment – you don’t need to line it if it’s nonstick.

Step 2

Stir the flour, cocoa, baking powder, bicarbonate of soda and fine sea salt together in a small bowl.

Step 3

In a slightly larger bowl, vigorously beat the butter, both the sugars and the vanilla with a small wooden spoon until you have a creamy mixture.

Step 4

Add a generous spoonful of the dry ingredients to the creamed butter and sugar and beat it in gently with your wooden spoon. Then, in about 3 batches, gently beat in the rest of the dry ingredients. Once they are absorbed, beat vigorously until you have a rich brown dough, then stir in the chocolate chips.

Step 5

Weigh this mixture, and divide it in 2; you don’t need to be fanatical about this, a few grams here or there won’t make a difference. Squidge each half in your hands to form 2 fat patties about 7cm/2¾in in diameter and place them on your baking sheet, at least 10cm/4in apart, as they spread while cooking.

Step 6

Sprinkle ⅛ teaspoon of sea salt flakes over each cookie and bake for about 12 minutes, until the top of each biscuit is cracked. At 10 minutes they will be utterly smooth, but in the next 2 minutes they seem to transform themselves. I crouch by the oven, staring through the glass door.

Step 7

Once the surface is cracked, the cookies are ready. They will, however, feel very soft – even uncooked – to the touch, and you will doubt me. But I will forgive you, as long as you obey me. Whip out the baking sheet, leaving the cookies in place for 5 minutes. Then slip a metal spatula under the cookies and transfer them to a wire rack. For optimal eating pleasure, leave for another 10 minutes before biting into one.