The claim that dark chocolate has health benefits appears to be true. The article they used is from the Popcorn for the People website, a nonprofit organization dedicated to creating jobs for adults with autism and developmental disabilities. Popcorn for the People sells popcorn products, one is a dark chocolate expresso flavor. So, this article could be biased since they're promoting one of their popcorn flavors, but the company is a nonprofit. Jason Katz, the Operations manager for Popcorn for the People, wrote the article. To trace the claim I went to an article from Healthline which is medically reviewed by a nutritionist and written by Kris Gunnars, who has a bachelor's degree in medicine. Both articles state that chocolate has the same nutritional value, such as iron, magnesium, zinc, phosphorus, and antioxidants. They both match that dark chocolate has heart health, and cognitive function bonuses.
Sources:
BSc, Kris Gunnars. “7 Proven Health Benefits of Dark Chocolate.” Healthline, 13 July 2022,
https://www.healthline.com/nutrition/7-health-benefits-dark-chocolate