¼ cup extra-virgin olive oil
1 small onion, finely chopped
4 garlic cloves, thinly sliced
2 sprigs basil
2 28-ounce cans whole peeled Italian San Marzano tomatoes
Kosher salt, freshly ground pepper
Heat oil in a medium heavy pot over medium. Cook onion, stirring occasionally, until very soft and fragrant, about 8 minutes. Add garlic and cook, stirring occasionally, until very soft, about 5 minutes. Stir in basil. Add tomatoes and their juice, crushing tomatoes with your hands as you go; season with salt and pepper and bring to a simmer. Reduce heat; simmer gently, stirring occasionally, until marinara is thick, about 1 hour. Season with salt and pepper. Serve with spaghetti.