Prep: Preheat oven to 400°F (200°C).
Mix Meatballs: In a large bowl, whisk the egg, flour, harissa, garlic, onion, and spices. Add the ground chicken and mix gently with your hands until just combined.
Season Veggies: Spread the chickpeas, cauliflower, sweet potato, and onion chunks across a large baking sheet (use two if needed). Drizzle with oil and spices, tossing to ensure everything is coated evenly.
Assemble & Roast: Roll the chicken mixture into roughly 16-18 meatballs (about 2 tbsp each). Nestle them into the veggie mix. Roast for 20 minutes.
Pro Tip: Switch to the broiler for the last 2 minutes for a charred, golden finish.
Sauce it Up: While roasting, whisk together all sauce ingredients in a small bowl.
Serve: Let the sheet pans cool for 2-3 minutes, then drizzle the sauce over the pan and garnish with chopped dates and fresh dill.