Bring a large pot of salted water to a rolling boil. Add pasta shells and cook until al dente, about 8–10 minutes. Drain and set aside.

In a large skillet, heat oil over medium heat. Add ground beef, onions, and garlic, cooking for 7–10 minutes until beef is browned and onions are translucent. Drain excess fat.

Pour in beef broth and sprinkle with Italian seasoning. Stir and let simmer for 5 minutes.

Lower heat to medium-low, add heavy cream, and stir continuously for about 5 minutes until sauce thickens.

Gently fold in the cooked pasta shells until well-coated and heated through, about 2–3 minutes.

Serve immediately, garnished with additional seasoning or cheese.