Cook penne pasta in a large pot of generously salted boiling water according to package directions until al dente. Drain thoroughly without rinsing and set aside.
Heat olive oil in a large skillet over medium-high heat. Add minced garlic and sauté for about 1 minute until fragrant and lightly golden, stirring constantly to prevent burning.
Add ground beef to the skillet, breaking it into small crumbles with a spatula. Cook until completely browned with no pink remaining, about 6-8 minutes. Drain excess fat if needed.
Season the browned beef with salt, black pepper, Italian seasoning, and crushed red pepper flakes if using. Stir well to distribute seasonings evenly throughout the meat.
Reduce heat to medium. Pour in beef broth and heavy cream, stirring to combine. Bring the mixture to a gentle simmer, allowing the liquids to blend together smoothly.
Add the drained penne pasta to the skillet, tossing until every piece is thoroughly coated with the creamy beef sauce.
Gradually stir in the freshly grated Parmesan cheese over low heat, stirring constantly until completely melted and the sauce becomes thick and creamy.
Sprinkle shredded mozzarella cheese evenly over the top of the pasta. Cover the skillet with a lid and remove from heat. Let rest for 5 minutes until the mozzarella melts into a gooey layer.
Remove lid and garnish with freshly chopped parsley just before serving.
