Preheat oven to 400°F. Toss zucchini, garlic, shallots, 5 tablespoons oil, and crushed red pepper in bowl. Spread on 2 large rimmed baking sheets; sprinkle with salt and pepper. Roast vegetables until tender, turning occasionally, 30 to 35 minutes. Toss cooked pasta in large bowl with 1 tablespoon oil. Transfer half of pasta (8 cups) to another bowl; cool, stirring occasionally. Cover; chill (reserve for mac and cheese). Place remaining pasta in large pot. Add roasted vegetables, 1/4 cup pasta cooking liquid, and 1 tablespoon oil; stir over medium heat until heated through. Add 3/4 cup basil and cheese. Toss, adding reserved cooking liquid by tablespoonfuls to moisten if dry. Season with salt and pepper. Transfer pasta to large platter. Sprinkle pasta with remaining 1/4 cup basil.