Heat oil over medium heat. Add onion and cook until soft and translucent, about 3 minutes.
Add ground beef, season with garlic, oregano, chili flakes, salt and pepper, and cook until well browned, breaking it up as it cooks.
Stir in tomato paste and cook for 1-2 minutes to deepen the flavor.
Add crushed tomatoes and grated carrot (if using), then stir. Pour in the cream, add nutmeg, reduce heat to low, and bring to a gentle simmer.
Taste the sauce and adjust spices if needed. Simmer gently for 10-15 minutes, stirring often, until thick and creamy.
Turn the heat to very low and stir in a handful of grated Parmesan.
Toss with hot pasta, adding a splash of pasta water if needed. Finish with extra Parmesan on top and serve while hot.
