In a large saucepan, heat the extra-virgin olive oil. Add the garlic cloves and cook over moderate heat, stirring occasionally, until golden, about 5 minutes. Add the tomato paste and cook, stirring, for 1 minute. Add the tomatoes and crush them with the back of a spoon; season with salt and pepper. Stir in the sugar and basil sprigs and bring to a boil. Simmer over low heat, stirring occasionally, until the sauce is thickened and reduced to 3 cups, about 30 minutes. Discard the basil sprigs and garlic.