140g unsalted butter, very soft
140g dark brown soft sugar
110g golden caster sugar
1 large egg
1 tsp baking powder
3/4 tsp bicarbonate of soda
3/4 tsp sea salt
250g plain white flour
180g dark chocolate, chopped
Cream the butter and sugars together until pale but not fluffy (light and fluffy will mean the cookies sink later!).
Add the egg and mix in.
Sift your flour, baking powder, bicarbonate of soda and salt together, and mix into the wet ingredients to make a dough.
Mix in the chocolate chips, then roll into balls of 60g and put on a baking tray lined with paper.
Do not put into the oven, put into the fridge overnight. Resting the cookie balls overnight will give you a much better rise, and a much nicer, chewier cookie! You can also freeze them for 30 days.
The next day, heat your oven to 160 fan, then bake your cookies for 12 minutes (even from frozen) - they might look underdone but they're not. Let them cool on the tray when you take them out, so they don't sink in the middle. Enjoy!