Melt 1 teaspoon butter in a skillet over medium-low heat. Add onion and sauté 10 minutes or until lightly browned. Add remaining 2 teaspoons butter, apple, banana, and garlic. Cook over medium heat, stirring often, 5 minutes or until slightly tender. Stir in curry powder and wine. Cook 2 minutes. Add chicken broth, salt, and pepper, and cook 2 to 3 minutes. Stir into couscous. Serve immediately; or press into ramekins, and unmold onto plates at serving time. If you prepare the couscous ahead of time, stir in additional chicken broth when reheating.