Preheat the oven to 375 degrees F (190 degrees C). Lightly grease a baking dish and set it aside.

Bring a large pot of salted water to a boil. Add the penne pasta and cook until just al dente according to package directions. Drain the pasta and set it aside.

In a large skillet over medium heat, melt the butter. Add the ground beef and cook, breaking it up as it browns. Season with salt and pepper.

Stir in the minced garlic and finely chopped onion. Continue cooking for 2 to 3 minutes, until the onion is soft and fragrant.

Pour in the heavy cream and beef broth, stirring well to blend. Add the Italian seasoning, red pepper flakes (if using), and additional salt and pepper to taste. Let the sauce simmer gently for about 5 minutes until it thickens slightly.

Add the cooked penne pasta to the skillet with the creamy beef sauce. Toss everything together until the pasta is well coated.

Transfer the creamy beef and pasta mixture into the prepared baking dish. Sprinkle the shredded cheese evenly over the top.

Bake uncovered for 10 to 15 minutes, until the cheese is melted, bubbly, and golden.

Let the baked pasta cool for a few minutes, then garnish with fresh chopped parsley. Serve hot.