Preheat oven to 400°. Toss mushrooms, garlic, olive oil, thyme, 1/2 tsp. salt, and 1/4 tsp. pepper together in an aluminum foil-lined broiler pan. Spread mushroom mixture in a single layer, and bake 20 minutes.
Meanwhile, cook couscous according to package directions.
Stir mushroom mixture, Worcestershire sauce, and remaining salt and pepper into couscous. Garnish, if desired.
Note: We tested with Casbah All Natural Original Toasted CousCous.