How to Make It
Preheat the oven to 400°. Set a fine sieve over a bowl and, using your fingers, remove the seeds from the tomatoes, working over the sieve. Gently press the seeds against the sieve to extract as much juice as possible. Set aside the tomatoes and juice and discard the seeds.
Coat the bottom of a 9-by-13-inch glass or ceramic baking dish with 1 tablespoon of the olive oil. Scatter the garlic, olives and jalapeño over the bottom. Season the cut sides of the tomatoes with salt and arrange them in the baking dish, cut sides down. Pour the white wine over the tomatoes along with the reserved tomato juice and arrange the chicken breast halves on top. Drizzle the chicken with 1 tablespoon of olive oil. Top each breast half with a thyme sprig and season with salt and pepper.
Cover the baking dish with foil and bake the chicken for about 50 minutes, or until it is cooked through and the tomatoes have released most of their juices. Transfer the chicken to a large plate, cover and keep warm. Let the tomatoes cool for about 2 minutes and carefully pull off their skins with your fingers. Add the tomatoes to the chicken and cover loosely to keep warm. Discard the thyme sprigs.
In a medium saucepan, bring the water to a boil with 1/4 teaspoon salt and the remaining 2 tablespoons of olive oil. Add the couscous, cover and remove from the heat. Let stand until the water is completely absorbed, about 5 minutes. Fluff the couscous with a fork and spoon it into shallow soup bowls. Top the couscous with the braised chicken and tomatoes, spooning the juices all over. Garnish with thyme sprigs and serve with lemon wedges.