1. Preheat your oven to 180˚C (160˚C fan), weigh and prepare all your ingredients in advance.
2. Place the butter in a heatproof bowl and melt over a small pan of simmering water (the bowl should not touch the water). When the butter is almost entirely melted through, add in the chopped up chocolate, stirring occasionally until entirely melted. Set the bowl aside.
3. In a food processor (or using a hand mixer), whisk the eggs, caster sugar and light brown sugar for 5 minutes (best to set a timer for this).
4. Pour the butter and chocolate mixture into the egg mixture. Add in 4/5 of the orange zest, leaving a little aside. Mix until well combined for approximately 1 minute.
5. In a separate bowl combine the flour, baking powder and sieved cocoa powder together. Add this to the wet mixture and mix for as little as possible, until evenly combined.
6. Using a tablespoon, or ideally an ice cream scoop, place evenly sized dollops of the dough onto a lined baking tray. Leave space between each cookie, as they will expand when baking. Flake a little coarse salt on each one and place the tray in the oven.
7. Bake for 11-12 minutes. The cookies should have crinkles, and the edges should be crispy.
8. Remove from the oven, sprinkle the remaining orange zest on and leave to cool on the baking tray for a few minutes, then transfer to a wire rack to cool completely.
Photography and recipe by Our Modern Kitchen.