Bring chickpeas and 4 cups water to a boil in a 4-qt. saucepan. Reduce heat to medium-low and cook, covered, until chickpeas are very tender, 1-1 1⁄2 hours. Drain, reserving 1⁄2 cup cooking liquid; cool to room temperature. Transfer all but 3⁄4 cup chickpeas to a food processor with the tahini, oil, juice, cumin, garlic, chile, and salt; purée until smooth. Add reserved cooking liquid and continue to purée until airy in consistency, about 5 minutes. Transfer hummus to a serving dish. Top with remaining whole chickpeas, drizzle with more oil, and sprinkle with salt.