In large bowl, combine ground chicken, bread crumbs, egg, scallions, Parmesan and chopped thyme. Stir until evenly blended. With wet hands, form into 1-inch meatballs, about 40 total. Set aside.
In large stock pot, heat oil over medium heat. Add carrots, parsnips and scallions. Cook 5 minutes, to soften. Add broth, thyme sprigs and 4 cups water; increase heat to high and bring to a simmer.
Gently drop meatballs into simmering broth mixture. Reduce heat to medium and cook 4 minutes. Add escarole in 2 batches, and the couscous. Cook 8 more minutes, then stir in Parmesan, salt and pepper. Serve warm.