Recipe adapted from 2 sources to accommodate my family's food allergies/intolerances (no gluten, nuts, or onions): Chef John's Italian Meatballs and I Breath I'm Hungry Giant Italian Meatball Gluten Free
Cover a baking sheet with foil and spray lightly with cooking spray.
Soak flour in milk in a small bowl for 20 minutes.
Mix beef and pork together in a large bowl. Stir flour mixture, eggs, parsley, garlic, salt, black pepper, nutmeg, Italian herb seasoning, and Parmesan cheese into meat mixture with a rubber spatula until combined.
Cover and refrigerate for about one hour. (optional).
Preheat an oven to 425 degrees F.
Using wet hands, form meat mixture into balls about 1 1/2 inches in diameter. Arrange onto prepared baking sheet.
Bake in the preheated oven until browned and cooked through, 15 to 20 minutes.