Bring a large pot of salted water to a rolling boil over high heat. Add penne pasta and cook according to package instructions until al dente, usually about 10–12 minutes. Reserve 1 cup of pasta water and drain the rest. Set the pasta aside.

In a large skillet, heat olive oil over medium heat until shimmering. Add the diced yellow onion and minced garlic, sautéing for about 5 minutes or until the onion becomes translucent.

Add the ground beef to the skillet with the sautéed onions and garlic. Cook for 7–9 minutes, breaking the meat apart with a spatula, until browned and fully cooked. Season with salt, pepper, and Italian seasoning.

Lower the heat to medium-low and gradually pour in the heavy cream, stirring as you go. Incorporate the reserved pasta water until you reach desired sauce consistency. Stir in Parmesan cheese until it melts into the sauce.

Add the cooked penne pasta directly into the sauce in the skillet, gently tossing until well-coated.

Scoop the creamy beef pasta onto plates, garnishing with additional grated Parmesan or parsley. Serve hot.