Cook the meatballs according to the recipe directions.
Meanwhile, heat the oil in a large skillet over medium heat. Add the fennel and cook until tender, 5 to 7 minutes.
Add the meatballs, tomatoes, and wine; season with ¾ teaspoon salt and ¼ teaspoon pepper. Cook until the tomatoes begin to burst, 7 to 9 minutes.
Meanwhile, cook the polenta according to the package directions; stir in the butter. Serve the meatballs over the polenta and sprinkle with the Parmesan and parsley.