In a large mixing bowl, combine ground chicken, breadcrumbs, grated Parmesan cheese, beaten egg, salt, black pepper, finely chopped onion, and minced garlic. Mix thoroughly and shape into 1- to 1½-inch meatballs, setting aside.

Heat olive oil in a large skillet over medium heat. Add the meatballs in a single layer and sear for 5-7 minutes, turning occasionally until browned. Remove and set aside.

In the same skillet, add another tablespoon of olive oil. Sauté chopped onion, chopped carrot, and chopped celery for 5 minutes until softened. Stir in tomato paste and cook for 1 more minute.

Pour in red wine and chicken broth, stirring to combine. Increase heat to medium-high and bring to a gentle simmer. Let reduce for 15 to 20 minutes.

Return the browned meatballs to the skillet, cover, and reduce heat to low. Let them braise for 20 to 30 minutes.

In a separate saucepan, bring water or chicken broth to a boil. Gradually whisk in polenta, stirring continuously. Simmer for 10 to 15 minutes until thick and creamy. Stir in grated Parmesan cheese and butter.

To serve, place creamy polenta on plates, top with meatballs and ladle over sauce. Garnish with chopped parsley.