Place the chocolate chips and butter into the food processor and pulse a few times to roughly combine. Add the eggs, coconut palm sugar, cocoa powder, starch, salt, espresso powder/coffee, vanilla, and blitz until combined. (I mix all my dry ingredients together first) . The batter is lumpy. Spread the mixture into the prepared baking dish. Sprinkle the chopped nuts over the top and gently press into the batter. Bake for 25 minutes or until the batter is set and feels slightly firm to the touch. The outer edges will appear drier than the inside. Let cool and then cut into 1 ½ inch squares.