Heat the vegetable oil in a Dutch oven over medium-high heat. Add the onion and ground beef and cook, breaking up the beef and stirring occasionally, until the onion is translucent and the beef is no longer pink, about 5 to 6 minutes. Remove some of the drippings if the beef is very fatty.
Add the garlic, bell pepper, and Italian seasoning to the beef and cook for 1 minute longer.
Add the bay leaf, salt, pepper, beef broth, tomato sauce, diced tomatoes, and macaroni. Stir to blend. Bring to a simmer, cover the pan, reduce the heat to low, and simmer for 20 minutes. Check to make sure the macaroni is tender, and add the cheddar cheese, stirring until the cheese has melted. Taste for seasonings.
Turn the goulash into a large serving bowl and garnish with chopped parsley or basil and extra cheese if desired.