Are there any snacks that use a large amount of black sesame seeds?
You can make black sesame seed soup. It's mildly sweet and is often eaten at breakfast by Chinese. Black sesame seeds are unhulled unlike most (white) sesame seeds sold in North America and Europe which are hulled. So if you eat the seeds whole, you'll get little benefit from them as they basically pass through your digestive tract unchanged. The soup uses ground seeds.

I know we're not supposed to give out requests for recipes but you're not asking so I hope I'm not wrong in giving you a link to the soup recipe. I have no idea if there are other sites with a recipe for it. http://www.chinasichuanfood.com/black-sesame-pastesoup/

A suggestion in toasting black sesame seeds. It's easy to toast white sesame seeds in a pan on the stove and tell by the colour change to a light golden brown when they're done. Black ones aren't so easy to tell by looks though. I found that adding some of the pale coloured seeds with the black ones is a good way to know. When the pale seeds start showing a light golden colour, you'll know the black are also toasted enough. Be careful not to over-toast them or they'll taste unpleasantly bitter.

There are other ways of using black sesame seeds but this is the easiest.