Position a rack in the upper third of the oven and preheat to 425 degrees . In a small bowl, stir together the caramel sauce, vinegar, cream and thyme. On a parchment-paper-lined baking sheet, season the chicken with salt and pepper. Brush both sides with the caramel mixture and arrange skin side up. Bake, brushing halfway through with the pan drippings, until golden-brown, about 20 minutes. Let rest for 5 minutes; reserve any juices.
Meanwhile, prepare the couscous according to package directions and keep warm. Divide among 4 plates; top each with a chicken breast and drizzle with the reserved juices.