Step 1

Purée tomatoes in a food processor until they’re as smooth or chunky as you like. Transfer tomatoes to a large Dutch oven or other heavy pot. (Or, use an immersion blender and blend directly in pot.) Add garlic, oil, and a 5-finger pinch of salt. Bring to a boil and cook, stirring occasionally, until sauce is reduced by about one-third, about 20 minutes. Stir in butter.

Step 2

Do Ahead: Sauce can be made 5 days ahead; cover and chill. Or let cool to room temperature and freeze up to 3 months.