In a large mixing bowl, add the room temperature butter and both granulated and light brown sugar. Whisk together with an electric hand whisk until smooth in texture and light in colour.
Add the eggs one at a time mixing in between eggs.
Gradually sift in the flour and baking powder and using a cool wooden spoon mix until fully combined.
Add the chocolate chips and mix in until thoroughly combined.
Divide the dough into equal portions.
Wrap the two portions tightly in cling film. Roll the dough into a large sausage shape. This will be sliced into cookies.
Add the rolled dough to the fridge for at least 30 minutes to help with the slicing.
When about to cook the cookies, preheat the oven to Gas Mark 4/180C/350F.
Remove the dough from the fridge and slice into 8 cookies.
Place the cookies onto a greaseproof lined baking tray allowing room for expansion as it cooks.
Sprinkle a little salt over each cookie and add to the oven for 20 minutes until golden brown around the edges.
When cooked remove from the oven and allow to cool on a wire rack.