Heat olive oil in a large skillet over medium-high heat.
Add ground beef to the skillet and cook, breaking it apart with a spatula, until browned and cooked through, about 5-7 minutes.
Add diced onion to the skillet and cook until softened, about 3 minutes.
Stir in minced garlic, dried Italian seasoning, salt, and black pepper; cook for 1 minute until fragrant.
Pour in the diced tomatoes with their juice and beef broth; stir to combine.
Add the uncooked penne pasta to the skillet and stir to submerge the pasta in the liquid.
Bring the mixture to a boil, then reduce heat to medium-low and cover the skillet.
Simmer for 15 minutes, stirring occasionally, until the pasta is tender and most of the liquid is absorbed.
Remove the skillet from heat and sprinkle shredded mozzarella and grated Parmesan cheese evenly over the top.
Cover the skillet again and let it sit for 3-5 minutes until the cheese melts.
Sprinkle chopped fresh parsley over the skillet before serving.