01 - Heat olive oil in a large, heavy-bottomed pot over medium heat. Add onion, carrot, and celery. Sauté for 6–8 minutes until softened and fragrant.
02 - Stir in minced garlic and cook for 1 minute until aromatic, being careful not to burn it.
03 - Add ground beef to the pot. Cook, breaking up with a wooden spoon, until browned and no longer pink, approximately 6–8 minutes.
04 - Stir in tomato paste and cook for 2 minutes to develop flavor. Pour in red wine, scraping up any browned bits from the bottom of the pot. Simmer until mostly evaporated, about 2–3 minutes.
05 - Add crushed tomatoes, oregano, basil, bay leaf, sugar (if using), salt, and pepper. Stir thoroughly to combine all ingredients.
06 - Bring to a gentle simmer, then reduce heat to low. Cover partially and cook for 45–60 minutes, stirring occasionally, until thickened and deeply flavorful. Adjust seasoning as needed.
07 - While sauce simmers, cook spaghetti in a large pot of salted boiling water according to package directions until al dente. Drain, reserving ½ cup of pasta water for consistency adjustment.
08 - Remove and discard bay leaf from sauce. If consistency is too thick, add a splash of reserved pasta water to loosen.
09 - Toss spaghetti with Bolognese sauce or plate pasta and top generously with sauce. Sprinkle with freshly grated Parmesan and garnish with basil or parsley if desired.