Prep: Preheat the oven to 425F and grease or line a large baking sheet. Place the chickpeas on a clean kitchen towel and pat dry; set aside.
Vegetable Prep: Add the cauliflower and red onion to a large bowl and add the smoked paprika, cumin, 1/2 teaspoon garlic powder and 1/2 teaspoon salt. Drizzle 1 1/2 tablespoons of oil over the veggies and mix well until evenly coated. Spread evenly across half of the baking sheet and set aside.
Chickpeas: Add the dry chickpeas to the same bowl (no need to rinse) along with the remaining 1/2 teaspoons of garlic powder and salt. Drizzle with the remaining oil and toss well. Spread evenly across the other half of the baking sheet.
Roast: Roast in the top rack of the oven for 20 minutes;. Flip the vegetables and toss the chickpeas, then return to the oven and bake for another 15 to 20 minutes.
Tahini Dressing: In the meantime, whisk the tahini, lemon juice, and salt together in a small bowl; the mixture will thicken. Continue to whisk the dressing and slowly add 3 tablespoons of water, until the dressing lightens in color and becomes pourable. Add more water to the dressing to thin as necessary. Set aside.
Assemble: Use a large spoon to spread half of the tahini dressing across the bottom of a large serving plate (or individual plates). Top the dressing with a thin layer of the roasted cauliflower and onion, then sprinkle the crispy chickpeas on top. Garnish the salad with the remaining dates, olives, and fresh parsley. Drizzle the remaining dressing on top.
Serve: Serve warm, or chilled if desired. Leftovers will keep in the fridge for up to 5 days.