Heat olive oil in a large skillet or saucepan over medium heat.
Add onion, garlic, carrot, and celery; sauté until soft and fragrant.
Add ground beef; cook until browned, breaking up clumps with a spatula.
Stir in tomato paste, crushed tomatoes, broth, oregano, basil, sugar, salt, and pepper.
Reduce heat and simmer uncovered for 30–35 minutes, stirring occasionally.
While sauce simmers, cook spaghetti according to package instructions; drain.
Taste sauce and adjust seasoning. Stir in fresh parsley or basil.
Serve Bolognese sauce over hot spaghetti and garnish with Parmesan or fresh basil.