Heat a large skillet over medium-high heat. Add the ground beef and cook, breaking it up with a spoon, until it is fully browned and no longer pink. Once browned, carefully drain off the excess fat to prevent the chili from being greasy.

Place the browned ground beef from Step 1 into the crock pot. Add the chopped onion, chopped red bell pepper, minced garlic, salt, black pepper, beef broth, crushed tomatoes, stewed tomatoes, drained and rinsed kidney beans, chili powder, optional cayenne pepper, and ground cumin. Stir well to combine all the ingredients evenly. I like to add the beans last so they don't break apart while stirring.

Cover the crock pot with its lid and cook the chili on low for 6-8 hours or on high for 3-4 hours, stirring once or twice during the cooking time if possible. This long simmer lets the flavors meld together and develops a hearty, rich chili. I find letting it cook for the full 8 hours on low gives the best depth of flavor.

Once the chili is cooked, ladle it into bowls. Top each serving with shredded cheddar cheese and a sprinkle of diced red onion for extra flavor and texture. Serve hot, ideally with a side of cornbread to soak up the delicious chili.