Chop the sirloin or round roast into ¼-inch cubes. Brown the chopped meat and ground chuck in a Dutch oven along with the onion, garlic and jalapeño pepper. Add the chicken broth, tomato sauce, chili sauce, diced tomatoes, and mild green chilies. Heat to boiling, reduce heat and simmer. Add the chocolate and stir in as it melts. In a small bowl, combine the cumin, chili powder, seasoned salt, celery salt, Kosher salt and pepper. Stir the seasonings into the chili, cover and continue to simmer for one hour.
To serve, cover bottom of bowl with Fritos, ladle the chili into the bowl and top with shredded Cheddar cheese.