In a large Dutch oven, heat the oil over medium heat. Add the sausage and cook, stirring to break into pieces, until browned and cooked through, 8 to 10 minutes. Using a slotted spoon, transfer the sausage to a paper towel lined plate to drain.  Add the onion and bell pepper to the Dutch oven. Cook over medium, stirring, until softened, 10 to 12 minutes. Stir in the garlic, cumin, chili powder, 1 teaspoons salt, 3/4 teaspoon pepper and cinnamon. Cook, stirring, for 30 seconds. Stir in the tomatoes, kidney beans, black beans, pumpkin puree, chicken broth and sausage. Bring to boil over medium-high. Reduce heat to medium-low, cover and cook, stirring occasionally, until the flavors meld, about 20 minutes. Season the chili with salt and pepper. Serve, garnishing with pumpkin seeds, sour cream, cheese and avocado, if desired.