Dice the onion and mince the garlic, then set aside.
In a skillet, brown the ground beef over medium-high heat until it is cooked through and no pink remains, breaking it apart with a wooden spoon as it cooks. Drain excess fat if necessary.
Add the chopped onion and minced garlic to the skillet with the beef, cooking until the onion becomes translucent and fragrant, about 3-4 minutes. The mixture will start smelling savory and look slightly softened.
Transfer the cooked beef mixture to your slow cooker, then add the diced tomatoes (with juices), kidney beans, pumpkin puree, cumin, cinnamon, smoked paprika, salt, and pepper. Pour in the broth and stir everything together until well combined.
Cover the slow cooker with the lid and set it to low. Let the chili simmer for 6 hours, allowing the flavors to meld and the pumpkin to break down into a velvety consistency.
Once cooking is complete, open the lid and stir the chili. It should be thick, with a rich, uniform color and tender ingredients.
Taste and adjust the seasoning with more salt, pepper, or spices if needed. Serve hot, garnished with your favorite toppings like cheese, sour cream, or fresh cilantro if desired.
