Brown the beef:

Place the ground beef in a large skillet over medium-high heat. Cook until fully browned, breaking it into small crumbles as it cooks, then drain off any excess grease.

Add beef to the slow cooker:

Transfer the cooked beef to a 5- to 6-quart slow cooker. Spread it out evenly across the bottom.

Prepare the sauce:

In a large mixing bowl, whisk together the beef broth and condensed cream of mushroom soup until the mixture is smooth and well combined.

Slow cook the beef mixture:

Pour the soup and broth mixture evenly over the beef in the slow cooker. Cover and cook on Low for 4–5 hours or on High for 2–3 hours.

Add the macaroni:

Stir the dry elbow macaroni into the hot beef mixture, making sure the pasta is fully covered by the liquid. Cover and cook on High for 25–35 minutes, stirring once halfway through, until the macaroni is tender.

Finish and serve:

Stir everything well before serving. If the sauce is thicker than you prefer, mix in a small splash of warm beef broth until creamy and smooth.