Use a fork to prick the sweet potato all over so steam can escape while the potato cooks. Put on a baking sheet, and bake for about 50 - 65 minutes, until the potato is tender all the way through, and a knife can easily pierce through the entire potato.
Scoop out the flesh of the potato and add to a food processor along with the remaining ingredients, the chickpeas, garlic, lemon, olive oil, water, salt, chili powder, and pepper.
Blend until completely smooth, stopping to scrape down the sides as needed. If you prefer a thinner hummus, just thin it with a bit more water or oil until desired consistency is reached.