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.
02 - Add garlic and cook for 1 minute until fragrant.
03 - Add ground beef and cook, breaking it up with a spoon, until browned and no longer pink, about 6–8 minutes.
04 - Stir in tomato paste and cook for 2 minutes. Pour in red wine, scraping up any browned bits, and simmer until mostly evaporated, about 2–3 minutes.
05 - Add crushed tomatoes, oregano, basil, bay leaf, sugar (if using), salt, and pepper. Stir well.
06 - Bring to a gentle simmer, then reduce heat to low. Cover partially and cook for 45–60 minutes, stirring occasionally, until thick and flavorful. Adjust seasoning as needed.
07 - Cook spaghetti in a large pot of salted boiling water according to package instructions until al dente. Drain, reserving 1/2 cup of pasta water.
08 - Remove bay leaf from sauce. If the sauce is too thick, add a splash of reserved pasta water.
09 - Toss spaghetti with a portion of the Bolognese sauce, or plate spaghetti and top each serving generously with sauce.
10 - Sprinkle with freshly grated Parmesan and garnish with basil or parsley if desired.