In a large bowl, combine the ground chicken, breadcrumbs, Parmesan cheese, egg, minced garlic, Italian seasoning, salt, pepper, and chopped parsley. Mix until well combined.

Form the mixture into meatballs, about 1 to 1½ inches in diameter.

Heat the olive oil in a large skillet over medium heat. Add the meatballs and cook until browned on all sides and cooked through, about 8-10 minutes. Remove meatballs from the skillet and set aside.

In the same skillet, add another tablespoon of olive oil and sauté the onions until translucent.

Add the sliced mushrooms and cook until they are browned and have released their moisture. Stir in the minced garlic and cook for an additional minute.

Pour in the chicken broth to deglaze the pan, scraping up any browned bits from the bottom of the skillet. Add the heavy cream, and Italian seasoning. Simmer the sauce until it begins to thicken, about 5 minutes. Season the sauce with salt and pepper to taste.

Stir in the fresh parsley and grated Parmesan cheese until the cheese has melted and the sauce is creamy.

Return the meatballs to the skillet with the sauce and simmer for another 5 minutes, until the meatballs are heated through and the sauce has thickened to your liking.