Place a large saucepan over medium-high heat. Add 2 tablespoons of olive oil and swirl to coat the pan. Heat until the oil is hot and shimmery.
Add one chopped medium onion and stir to coat. Sauté, stirring occasionally, for 8 to 10 minutes until the onion is very soft.
Reduce the heat to medium. Add 3 minced large garlic cloves and stir. Sauté for 60 seconds until fragrant, stirring constantly.
Add two 28-ounce cans of whole peeled San Marzano tomatoes and stir. Increase the heat to high and bring the mixture to a boil, stirring occasionally.
Reduce the heat to low immediately once boiling. Simmer for 20 minutes, stirring occasionally and breaking up the tomatoes with a wooden spoon or spatula.
Stir in ¼ cup of chopped fresh basil leaves. Simmer for an additional 5 minutes, stirring occasionally.
Remove the saucepan from the heat. Stir in 1 ½ teaspoons of kosher salt and ½ teaspoon of freshly ground black pepper. Allow the mixture to cool slightly.
Insert an immersion blender into the saucepan and purée until the sauce is thick and mostly smooth (refer to notes if using a standard blender).
Taste the sauce and adjust the salt or pepper as needed. Stir in the cooked pasta of your choice until thoroughly coated in the pomodoro sauce.
Portion the pasta and sauce into serving bowls or plates. Top with grated parmesan if desired and serve immediately.
