Brown the meat: In a skillet over medium heat, cook the ground beef (or turkey) with the chopped onion until the meat is browned and the onions are softened, about 5-7 minutes. Drain any excess fat and add the minced garlic, cooking for another 1-2 minutes until fragrant.

1. Add ingredients to the slow cooker: Transfer the cooked meat mixture to the slow cooker. Add the pumpkin puree, diced tomatoes with their juices, kidney beans, black beans, and beef or vegetable broth.
2. Season the chili: Stir in the chili powder, cumin, smoked paprika, cinnamon (if using), salt, pepper, and red pepper flakes (if using). Mix well to combine all the ingredients.
3. Cook the chili: Cover and cook on low for 6-8 hours or on high for 3-4 hours, until the chili is thickened and the flavors are well developed.
4. Adjust seasonings: Taste the chili and adjust the seasonings with more salt, pepper, or spices if desired.
5. Serve: Ladle the chili into bowls and garnish with fresh cilantro, a dollop of sour cream, or a sprinkle of shredded cheese if desired. Serve with cornbread or tortilla chips on the side for extra comfort.