Put the butter in a large saucepan. Find two heatproof bowls, one larger, one slightly smaller. Fill the large one with ice and a cup of water. Put the smaller one next to you near the hob.

Melt the butter on medium heat. Once foaming, keep stirring with a plastic spatula – you want to keep the milk solids moving throughout the pan. This will take about 5-6 mins. Be brave – don’t take it off when it is just golden; you’re looking for more of an amber colour. At this stage, and when it smells a lot like digestive biscuits, pour it into the smaller bowl. Immediately put the smaller bowl on top of the ice in the larger bowl.

Whisk the butter over ice slightly to help it cool. This will take about 3-4 mins. You’re looking for it to turn into the texture of a slightly loose cream cheese icing. Once creamy, but not fully solid, scrape it into the bowl of a stand mixer with both sugars. You can use an electric whisk, if you prefer, but if you have a stand mixer, use it. Once creamy, whisk in the eggs and vanilla, leaving it to whip for a good 8 mins, until it’s thick and creamy.

Pour in the plain flour, 1 tsp salt and the bicarb. Gently fold the dough together with a spatula, then fold through the chocolate. You don’t want to overmix the dough. Cover with baking parchment and keep chilled in the fridge overnight.

Heat the oven to 180C/160C fan/gas 4. Use a cookie scoop to scoop craggy balls of dough onto two lined baking sheets. Don’t try and form them into smooth balls – a rough ball is what you’re going for. Texture means they have a better appearance at the end. You should get roughly 15.

Bake for 12-15 mins until lightly golden. When they come out of the oven, give the tray a good whack on your kitchen counter. This will help create a crispy edge and a rippled appearance that is quite attractive. While the cookies are still warm, sprinkle generously with sea salt flakes. Leave to cool on the tray for a few minutes, then transfer to a wire rack to cool completely.