Preheat oven to 400 degrees F. Lightly spray baking sheet with olive oil cooking spray; set aside.
In a small pot, bring the broth to a boil. Stir in couscous. Remove from heat and cover. Let stand 5 minutes. Fluff with fork; set aside.
Place asparagus and scallions on prepared baking sheet. Toss with 1 tablespoon salad dressing. Roast in preheated oven for 10 to 12 minutes.
In a large bowl, combine cooked couscous, roasted vegetables, cherry tomatoes, basil, and remaining salad dressing. Toss to combine.
Serve warm or at room temperature.