Chop the onion, mince the garlic, and chop the fresh basil. Open the cans, measure the water and Worcestershire sauce, mix the dried seasonings in a small bowl, and grate the Parmesan.
Heat olive oil in a Dutch oven over medium-high heat. Add the beef, onion, and 1/2 teaspoon salt, breaking the beef into crumbles, and cook 8 to 10 minutes until no pink remains. Spoon off all but about 1 tablespoon of fat.
Reduce heat to medium, add the garlic and optional red pepper flakes, and stir constantly for 30 seconds until fragrant, without letting the garlic brown.
Add the tomato paste and stir and press it against the bottom of the pot for 2 minutes, until it turns brick red and a slight film sticks to the pot.
Pour in the crushed tomatoes and tomato sauce, add the water (swirled in the sauce can first), Worcestershire sauce, dried basil, dried oregano, sugar, remaining salt, black pepper, and bay leaf. Scrape the bottom and bring to a gentle bubble over medium-high heat, about 3 to 4 minutes.
Reduce heat to low and simmer uncovered for 35 minutes, stirring every 5 minutes and scraping the bottom. The sauce is done when a spoon dragged across the bottom leaves a trail that fills in slowly.
With about 15 minutes left, boil 4 quarts of water with 2 tablespoons salt, cook the spaghetti until al dente, scoop out 1 cup of pasta water, and drain without rinsing.
Remove the pot from the heat, discard the bay leaf, and stir in the fresh basil. Taste and adjust with salt or up to 1/4 teaspoon more sugar, and loosen with reserved pasta water if too thick.
Toss the drained spaghetti with the sauce over low heat for 1 minute, or ladle sauce over plated spaghetti. Top with grated Parmesan and serve right away.