Heat a large skillet over medium-high heat, add oil, and brown the ground meat for about 5-7 minutes until it develops crispy edges and releases flavorful juices.
While the meat cooks, dice the onion and mince the garlic. Add the onion and garlic to the skillet and sauté for about 3-4 minutes until fragrant and golden, filling the kitchen with warm, savory aromas.
Transfer the browned meat along with the sautéed aromatics into the slow cooker. Stir in the pumpkin purée, fire-roasted tomatoes, rinsed beans, broth, chili powder, cumin, and cinnamon if using, combining everything well.
Set the slow cooker to low and cook for 6 to 8 hours, allowing the flavors to meld and the chili to thicken, filling your kitchen with smoky, spicy aroma.
After 6 hours, check the chili; it should be thick, bubbling around the edges, and fragrant. If it’s too thick, stir in a splash of broth. If too runny, uncover and cook on high for 30 minutes to thicken further.
Taste the chili and adjust seasonings with salt or additional spices as needed, ensuring a perfect balance of smoky, spicy, and sweet flavors from the pumpkin.
Once ready, turn off the slow cooker and let the chili rest for about 10 minutes to settle. Serve hot, garnished with chopped cilantro or a dollop of sour cream for extra flavor and creaminess.