Preheat grill to medium-high. While grill heats, combine 2 tablespoons olive oil and lemon zest in a large rectangular dish; add squash and turn to coat. Season squash with salt and pepper.
Finely grate garlic cloves (you should have about 1 teaspoon). Toss chickpeas with 1 tablespoon oil, 1/2 teaspoon garlic, cayenne, paprika and cinnamon. Season with salt and pepper. Place a large square of foil on a work surface; place chickpeas in the center. Crinkle and gather the edges of the foil to create a packet. (Reserve bowl.)
Add squash to one side of the grill and packet on the other. Grill, turning squash and shaking packet occasionally, until squash is tender and chickpeas are lightly browned, about 8 to 12 minutes. Transfer squash to a serving platter and return chickpeas to reserved bowl. Toss chickpeas with parsley and raisins; scatter over squash. In a small bowl, stir together yogurt and remaining 1/2 teaspoon garlic; season with salt and pepper. Spoon yogurt over vegetables, drizzle with olive oil if desired, and serve with lemon wedges.
Before her diagnosis, Caroline wrote a book on cakes called Cake Magic!. She started developing a birthday cake using her gluten-free mix found in that book. Check out other recipes she’s developing for her new life—and the stories behind them—on her blog, The Wright Recipes. Her next book, Catalan Food, written with chef Daniel Olivella, comes out in early September from Clarkson Potter.