Preheat oven to 425°F.
Arrange the broccoli, sweet potatoes, and chickpeas on separate sheet pans. Drizzle each with 1 tablespoon olive oil.
Season the sweet potatoes with ½ tablespoon garlic powder and ½ teaspoon salt. Season the chickpeas with ½ tablespoon garlic powder and ½ teaspoon salt. Finally, season the broccoli with ½ tablespoon ground cumin and ½ teaspoon salt. Toss each sheet pan to coat evenly.
Roast the sweet potatoes for 30 minutes and the broccoli and chickpeas for 25 minutes, stirring halfway through, until tender and lightly browned.
Add 1½ cups water or vegetable broth to a pot and bring to a boil. Stir in the pearl 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 ½ 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.