Preheat the oven to 400 F/205 C.
Smash the garlic and roughly chop the shallot.
5 garlic cloves, smashed, 1 shallot, chopped
Combine the tomatoes, smashed garlic, shallot, salt, pepper, sugar, and Italian seasoning in a 9 inch cast iron skillet, dutch oven, or oven-proof baking pan.
28 ounce can San Marzano whole tomatoes, ¼ teaspoon salt, ¼ teaspoon pepper, ½ teaspoon sugar, 1 ½ tablespoon Italian seasoning
Bake the sauce for 30 minutes, or until the sauce is thick and has reduced.
Transfer the sauce to a blender and blend until smooth, about 30 seconds.
Makes 3 cups of sauce. Store the sauce in a sealed container or jar in the fridge for 5 days or in the freezer for up to 3 months!