Heat the olive oil in a large heavy-bottomed pot over medium-high heat.
Add the onion and garlic and sauté for about 1½ minutes until fragrant.
Add the ground beef and cook, breaking it apart with a spoon until browned.
Stir in the Italian seasoning and cook for 30 seconds.
Add the tomato paste and cook for 1 minute to deepen its flavor.
Pour in the crushed tomatoes, chicken broth, salt, black pepper, and red pepper flakes if using.
Stir well and add the pasta.
Bring to a gentle simmer and cook for about 15 minutes, stirring frequently to prevent sticking, until the pasta is nearly tender.
Stir in the heavy cream and simmer for another 1–2 minutes until the sauce becomes rich and creamy.
Remove from the heat and let the pasta rest for 2–3 minutes before serving.
Garnish with freshly grated Parmesan cheese and chopped parsley.