Preheat the oven to 180°C/Fan 400/ Gas Mark 6. Line two large baking trays with baking paper.
Next, using an electric handheld whisk in a large bowl, beat the butter until it’s really soft. Add the sugars and beat for a further 2 minutes, then add the egg and vanilla and beat until combined.
In a separate large mixing bowl, combine the flour, baking powder, bicarbonate of soda and fine salt. Using a fork or balloon whisk, thoroughly mix together all the ingredients to ensure the bicarbonate of soda is evenly distributed.
Tip the dry ingredients into the butter mixture along with the chocolate, then stir with a wooden spoon until combined.
Using your hands, push together any bits that are sitting in the bottom of the bowl until you have a dough.
Roll the dough into 10 equal-sized balls and place them on the lined baking trays, leaving space between each one to allow for spreading.
Bake in the preheated oven for 14 minutes. After this time, the cookies may look slightly under-baked, but they will crisp up at the edges as they cool.
Remove from the oven and sprinkle the cookies with the sea salt flakes and allow to cool.
These cookies keep well in an airtight container for up to 4 days.
Tip: You can also make and freeze the dough ahead, then bake the dough balls in smaller batches – just add an extra 4 minutes to the baking time when baking from frozen. Tahini works really well with these cookies, just beat two tablespoons of tahini into the butter before adding the sugar. You can also sprinkle with white or black sesame seeds too.
Lazy Baking by Jessica Elliott Dennison (Hardie Grant, £16.99) Photography ©Matt Russell.