Nice writeup. Dark chocolate is indeed amazing I started my own nutrition education about mid-way through my undergraduate degree and it was one of the best decisions I could ever make so I definitely relate with you on that.
My own take on brain health lies more on the eggs and fish side of the story since the brain is made up of mostly cholesterol and fat. Eggs contain a lot of choline which is used for neurotransmission. Fish is rich in omega-3 fats.
Of course we still need antioxidants to protect these important fatty components of our brain!