Combine all meatball ingredients in a large bowl and mix until just combined.
Roll into 1½-inch meatballs.
Heat oil in a large skillet over medium-high heat. Sear meatballs until browned on all sides. Remove and set aside.
In the same skillet, melt butter. Add onion and cook 2–3 minutes. Add garlic and mushrooms and cook until softened and golden.
Stir in flour and cook for 1–2 minutes.
Add Worcestershire sauce, then slowly stir in beef broth. Add heavy cream, Italian seasoning, salt and pepper.
Return meatballs to the skillet. Cover and simmer over medium-low heat for 12–15 minutes, until cooked through and gravy has thickened.
Garnish with parsley and serve over mashed potatoes or rice.
