This recipe is probably my favourite cookie recipe as they always turn out so great! I was a bit unsure about using cups to measure out the ingredients with at first (I normally use ounces or grams) but the cookies turned out fine.
I can't remember where I got the original recipe from unfortunately, as I printed it out a while ago.
Pre-heat your oven to 375 degrees or gas mark 5. Grease or line 2 baking trays.
In a large bowl, beat the butter and sugars together until creamy. Add the egg white and vanilla extract and mix until blended well.
In another bowl, combine flour, baking soda, salt and cocoa powder. Gradually add the flour mixture to the egg and sugar. The recipe didn't state to use any milk, but I found it practically impossible to mix without any, so I added a few drops to make it easier. Stir in the chocolate chips.
Drop cookie dough by the teaspoonful (I used my hands and rolled into ball shapes as the mixture is quite sticky!) on to your greased baking tray.
Bake for 10-12 minutes. When cooked, leave cookies on the baking tray for a minute or so, then transfer to a wire rack to cool completely.