Preheat your oven to 400°F and line a large baking sheet with parchment paper for easy cleanup.
Cut the chicken breast and sweet potato into uniform 1-inch cubes to ensure even cooking.
In a large mixing bowl, toss the cubed chicken, sweet potato, broccoli florets, and drained chickpeas with the olive oil, sea salt, black pepper, and garlic powder until well coated.
Spread the mixture in a single layer on the prepared baking sheet, ensuring the pieces are not overcrowded so they roast rather than steam.
Roast in the oven for 20 to 25 minutes, or until the chicken is cooked through and the sweet potatoes are tender and lightly caramelized.
While the bowl components roast, whisk together the tahini, lemon juice, and water in a small ramekin until the dressing is smooth and pourable.
Transfer the roasted chicken and vegetables to a serving bowl and finish by drizzling the creamy tahini dressing over the top.