Heat olive oil in a large pot or deep skillet over medium-high heat.
Add ground beef and cook, breaking it up with a spoon, until browned and no longer pink, about 5-7 minutes.
Add diced onion 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 diced tomatoes with their juice and beef broth, stirring to combine.
Add uncooked penne pasta and stir to submerge the pasta in the liquid.
Bring the mixture to a boil, then reduce heat to medium-low and simmer uncovered, stirring occasionally, until pasta is tender and most of the liquid is absorbed, about 15 minutes.
Remove from heat and stir in grated Parmesan cheese until melted and combined.
Sprinkle chopped fresh parsley on top before serving.