Heat olive oil over medium heat in a large skillet.
Add onion and garlic and sauté over medium heat for about 10 minutes, until soft.
Add tomatoes OR PASSATA and reduce heat to low. ADD ¾ WATER Simmer for 10 minutes. TO REDUCE WATER.
Turn off heat and add basil. Allow basil to steep in tomato sauce for about 15 minutes.
Add a half cup of parmesan cheese and 1 tablespoon of sugar.
Taste and add more sugar if needed.
Meanwhile, bring a pot of water to boil. Add salt and spaghetti and cook until about 2 minutes before tender.
Reserve 1 cup of pasta cooking water before draining.
Return pomodoro sauce to skillet and along with pasta.
Toss pasta in sauce over medium heat adding the butter and another ¼ cup of parmesan cheese.
Stir in some of the pasta cooking water as needed to achieve a smooth consistency.
Continue tossing until pasta is completely coated in sauce, about 2 minutes more.
Season generously with salt and pepper to taste.
Serve immediately with remaining parmesan cheese as a garnish.
