Preheat over to 425°.
Heat oil in a pot over medium heat and saute garlic with shawarma spice until fragrant. Stir in rinsed rice and cook another 1-2 minutes. Pour in vegetable broth with a heavy pinch of salt, stir, bring to a boil, then reduce heat to low, cover and cook for 15-18 minutes until rice is tender. Keep covered off the heat.
While the rice cooks, drain, rinse, and pat dry chickpeas and spread across baking dish along with sliced onion, diced zucchini, and halved tomatos. Drizzle with olive olive and sprinkle evenly with shawarma spice and a good pinch of salt. Stir to evenly coat. Roast in oven for 20 minutes.
For the garlic sauce, combine greek yogurt, garlic, and cayenne pepper in a bowl. Stir in water until it is a drizzly consistency and adjust to for salt.
To serve, fluff rice with fork and serve with roasted vegetables and drizzle with sauce.