Heat the olive oil in a large pot over medium heat. Add the ground beef and cook until browned, breaking it apart with a wooden spoon, for about 5-7 minutes. Drain excess grease if necessary.
Stir in the ranch seasoning, garlic powder, and onion powder, mixing well to coat the beef.
Add the uncooked penne pasta, beef broth, and milk to the pot. Stir to combine and bring the mixture to a boil.
Once boiling, reduce the heat to low, cover, and let it simmer for about 10-12 minutes, or until the pasta is cooked and has absorbed most of the liquid. Stir occasionally to prevent sticking.
Remove the pot from heat, and stir in the shredded cheddar cheese until melted and combined.
Season with salt and pepper to taste.
If desired, garnish with chopped green onions before serving.