Dice the onion into small pieces and set aside. Mince the garlic cloves finely to release their aroma.
In a skillet, heat the olive oil over medium heat until shimmering. Sauté the diced onion until it becomes translucent and fragrant, about 5 minutes.
Add the minced garlic to the skillet and cook for another 30 seconds, stirring constantly until it releases a fragrant aroma but doesn’t burn.
Transfer the cooked onion and garlic mixture to the slow cooker. Add the rinsed beans, diced tomatoes with their juice, and roasted pumpkin chunks.
Sprinkle in the cumin, cinnamon, chili powder, smoked paprika, and salt, then stir everything together to evenly coat the ingredients with the spices.
Cover the slow cooker with its lid and set it to low. Let the chili simmer gently for about 4 hours, allowing the flavors to meld and the pumpkin to soften further.
Once cooking is complete, open the lid and give the chili a gentle stir. The mixture should be thickened and fragrant, with the pumpkin adding a velvety texture.
Ladle the warm, hearty chili into bowls and serve immediately, garnished with additional toppings if desired.
