Heat a large, heavy-bottomed pot over medium heat. Add the ground beef, breaking it apart as it cooks. Continue cooking until browned and fully cooked.
Stir in the diced onion, bell peppers, celery, jalapeños, and mushrooms. Cook until softened, allowing the vegetables to release their flavors.
Pour in the diced tomatoes, stewed tomatoes, tomato sauce, and water, stirring until well combined.
Sprinkle in the chili powder, lots of salt & black pepper, and cayenne for extra heat. Stir in the shredded chicken, kidney beans, and pinto beans.
Bring the chili to a gentle boil, then reduce the heat to a low simmer. Allow it to cook uncovered for at least one hour, stirring occasionally to deepen the flavors and thicken the texture.
Taste and adjust seasoning as needed. Ladle into serving bowls and garnish with optional toppings such as shredded cheddar cheese, sour cream, greek yogurt, or fresh green onions.