In a 12-inch cast iron skillet over medium heat, cook the ground beef along with the diced onion, garlic powder, salt, and black pepper until the beef is fully browned and no longer pink, about 7 to 9 minutes.
Reduce the heat to low and stir in the cream cheese and heavy whipping cream until the cream cheese melts and the mixture is creamy and well combined.
Spread the drained green beans evenly over the beef mixture.
Sprinkle the shredded Cheddar cheese on top of the green beans. Cover the skillet and continue cooking on medium heat for 13 minutes or until the cheese is melted and bubbly.