For the vinaigrette: Toast the seeds over medium heat in a heavy medium skillet, stirring occasionally, until the seeds darken in color and become fragrant, 3 1/2 to 4 minutes. Place the seeds on a plate; cool for 1 minute. Grind the seeds finely in a small food mill or grinder.
Whisk the oil, vinegar, salt, pepper, cinnamon, cloves and the toasted seeds until thick and blended in a small bowl. Stir in the shallots. Set the vinaigrette aside.
For the salad: Place an oven rack in the center of the oven and preheat to 400 degrees F.
Bring the broth to a simmer over medium-high heat in a heavy medium saucepan. Mix in the quinoa. Reduce the heat to medium-low. Cover and simmer until the water is absorbed and the quinoa is tender, about 15 minutes. Turn off the heat and let the quinoa stand, covered, 5 to 10 minutes. Cool and fluff with a fork.
Meanwhile, spray a large rimmed baking sheet with vegetable oil spray. Toss the eggplant with 3 tablespoons oil, 1/4 teaspoon salt, and the pepper on the sheet. Roast until tender and browned, stirring once, about 30 minutes.
Transfer the quinoa to a large bowl; fluff with a fork. Add the vinaigrette, eggplant, apples, walnuts and cranberries. Toss to blend.
Cover the bottom of a shallow platter with the watercress. Spoon the salad on top and serve.