Cook onion and garlic in 1 tablespoon warm olive oil until tender. Season with 1/2 teaspoon each salt and pepper. Add tomatoes and a dash of sugar; cook 10 minutes. Add 1/2 cup chopped fresh basil. Season shrimp with salt and pepper, to taste, and sauté with 1 tablespoon warm olive oil in a separate pan for 3 minutes or until opaque. Add shrimp to tomato mixture, and toss with cooked pasta. Garnish with additional basil.