I have been cooking and eating broccoli leaves and am happy to learn that others are interested.  I lived in Kenya for 13 years, and various greens were fair game to eat with their basic "polenta" or (ugali) made with white maze meal.  Greens used were collard greens of verious types, and when I returned to Oklahoma and had my own garden that grew huge broccoli with good compost, which had very large leaves, along with cauliflower, turnip greens or brussel sprout...