If you're ensorcelled by something, you're so fascinated that it seems like you're under a magic spell. Your cat may be totally ensorcelled by the hummingbirds flitting around the feeder just outside your window.
The adjective ensorcelled and its related verb, ensorcell, come from the French ensorcerer, "bewitch." It shares a root with sorcery, as well as a sense of magic or the supernatural. If you find yourself mesmerized by something, feel free to use this old fashioned word to capture the feeling: "It may seem silly, but I'm completely ensorcelled by those cooking shows on TV."