Preheat oven to 350°F. Place sausage links in an unheated skillet. Add ½ inch of water to the skillet. Bring to boiling; reduce heat. Cover and simmer about 15 minutes or until juices run clear; drain off liquid. Cook for 2 to 4 minutes more or until browned, turning occasionally. Remove from heat. When cool enough to handle, cut sausages in half lengthwise; bias-cut into ½-inch-thick slices. Set aside.
In a large skillet, cook garlic in hot olive oil for 1 minute. Stir in undrained tomatoes, the 3 tablespoons parsley and, if desired, the crushed red pepper. Bring to boiling. Stir in eggplant. Reduce heat. Cover and simmer for 15 minutes.
Meanwhile, cook pasta according to package directions, cooking it for the minimum time listed; drain. Return pasta to hot pan. Stir in eggplant mixture and sausage. Spoon into a 2-quart baking dish.
Bake covered with foil about 30 minutes or until heated through. Sprinkle with Parmesan cheese. Uncover and bake about 5 minutes more or until cheese melts. If desired, sprinkle with additional parsley.