Bring a large pot of salted water to a boil. Add penne pasta and cook until al dente, about 10-12 minutes. Reserve 1 cup of pasta water, drain the rest, and set aside.

In a large skillet, heat olive oil over medium heat. Add diced onion and minced garlic; sauté for about 5 minutes until onion is translucent.

Add ground beef to the skillet. Season with salt, pepper, and Italian seasoning. Cook until browned, about 7 minutes.

Lower heat to medium-low and add heavy cream. Let simmer for about 2 minutes, then gradually mix in reserved pasta water and parmesan.

Add the drained penne pasta to the skillet, tossing to coat in the creamy sauce. Stir for another 2-3 minutes to combine flavors.

Serve hot, garnished with extra parmesan or parsley if desired.