Preheat oven to 375°F. Add sweet potato chunks to a baking sheet, toss with 1 teaspoon of olive oil and sprinkle with sea salt. Roast for 25-30 minutes, until tender. This step can be done a day or two in advance.
Start prepping chili by adding 1 Tablespoon olive oil to a skillet. Once oil is hot, add in the chopped onion, bell peppers and garlic. Sauté for 5-7 minutes until onions are fragrant and translucent. Add chili powder, salt, cayenne and cinnamon. Toss to combine and cook for 1 minute longer.
Transfer cooked onions and peppers into your slow cooker. Add in roasted sweet potato chunks, black beans and diced tomatoes. Cook on high for 2-3 hours or low for 4-5 hours.
When ready to serve, top with your favorite chili toppings like avocado, cilantro, jalapeño or even cashew sour cream.