Preheat the oven to 400°F. Grease an 8x8x2-inch baking pan with the olive oil; set aside.
Place the chickpeas in a large bowl. Mash them well with a potato masher or a fork. Stir in the egg, breadcrumbs, cilantro, garlic, tahini, lemon juice, cumin, and salt. Form into 12 1 1/2-inch balls, and place them snugly into the prepared pan in rows, making sure the balls are touching. Bake for 18 to 20 minutes or until the balls are cooked through (160°F). Let rest in the pan for five minutes before serving.
In a small bowl stir together the yogurt, agave nectar, and lemon zest. Serve with the falafel balls.