1) Preheat oven to 190 degrees F.
2) In a large mixing bowl, with an electric mixer, cream the butter and fat together with the brown sugar. Add the eggs 1 at a time and mix well. Add the vanilla and chocolate essence and raspberry flavoring, mix well.
3) In a separate bowl, combine the flour, salt, bicarbonate of soda and cocoa powder. Slowly add to butter mixture and mix thoroughly. With a rubber spatula, stir in the chocolate chips and nuts.
4) Scoop onto a baking paper lined baking tray with an ice cream scoop and bake for 10 to 12 minutes. Transfer to a wire rack to cool.