Heat a large skillet over medium heat. Add oil, peppers and onions and cook, stirring often, until softened.
Stir in ground beef (cooked or raw), taco seasoning and salt. If you have some Big Batch Beef prepped, you can just cook and stir 1 minute. If you are starting with raw ground beef, cook and stir until browned.
Add milk, tomatoes and beef broth and bring to a simmer over medium-high heat. Stir in dry macaroni.
Cover and cook, stirring often, until pasta is cooked through -- about 10 minutes.
Stir in cheese (you can add a splash of broth or milk if you need to make the sauce come together) and let melt, reserving 1 cup to sprinkle over top if desired. Serve.