Preheat your oven to 400°F (200°C), then toss the diced sweet potatoes with olive oil, salt, and pepper. Spread them out on a baking sheet and roast for about 20-25 minutes, until they are tender and slightly caramelized around the edges.
While the sweet potatoes are roasting, prepare your slow cooker by adding the drained and rinsed black beans, diced tomatoes with juice, and vegetable broth to the pot. Stir in the ground cumin, cinnamon, chili powder, and a pinch of salt and pepper to start building the flavors.
Once the sweet potatoes are done roasting, carefully add them into the slow cooker, mixing gently to combine all the ingredients. The warm roasted sweet potatoes will start to absorb the flavors as they sit together.
Cover the slow cooker with its lid and set it to low heat. Let everything simmer for about 6 to 8 hours, allowing the flavors to meld and the sweet potatoes to become even softer and more flavorful.
After the cooking time, open the lid and stir the chili gently. Check that the sweet potatoes are tender and the flavors are well developed—adjust seasoning with extra salt, pepper, or chili powder if needed.
Use a ladle to serve the sweet potato chili into bowls, enjoying its thick, chunky texture with a warm, inviting aroma of spices and roasted sweet potatoes.
