Preheat oven to 425° F.
Add the broccoli, sweet potatoes, and chickpeas to three separate baking dishes. Drizzle each with 1 tbsp olive oil.
Season the sweet potatoes with 1/2 tablespoon garlic powder, the chickpeas with 1/2 tablespoon garlic powder, and the broccoli with 1/2 tablespoon cumin. Add salt and pepper to taste, then toss each tray to coat evenly.
Bake the broccoli and chickpeas for 25 minutes and the sweet potatoes for 30 minutes, or until tender and lightly browned.
Add 1 1/2 cups water or vegetable broth to a pot and bring to a boil. Stir in the couscous, cover, reduce the heat, and simmer for 8-10 minutes, stirring occasionally, until the liquid is absorbed.
Add all sauce ingredients to a blender. Start with 1/2 cup water, then slowly add more as needed until smooth and the desired consistency is reached.
Assemble the bowls by layering couscous, sweet potatoes, broccoli, and chickpeas. Drizzle with sauce and serve.