Place garlic in baking dish with olive oil and bake at 375 degrees for 10 minutes. Add artichokes, white wine, half the vegetable broth and half the lemon quarters. Bake for 30 minutes. Remove dish from the oven and take out the lemon quarters. Add olives and sun-dried tomatoes, plus remaining broth and return the dish to the oven and heat through. Remove from the oven and pour half the liquid into a saucpan. Return pan to oven and let roast for 15 minutes more. Add enough broth to make 2 1/2 cups in the saucepan. Heat until almost boiling, squeeze remaining lemon quarters into the pan. Pour this over the couscous, dot with butter, cover and let rest for 10 minutes. Serve couscous, topped with artichoke mixture.