Preheat the oven to 350 degrees F. Grease a roasting tray with cooking spray.
In a small bowl, add breadcrumbs and enough milk to submerge the breadcrumbs. Set aside and allow the breadcrumbs to rehydrate for roughly 30 minutes, then press the breadcrumbs and discard any excess milk.
In a large mixing bowl, combine the pork, lamb, beef, parmesan, garlic, parsley, and rehydrated breadcrumbs. Season with salt and pepper, then mix until evenly incorporated.
Using your hands, shape the meatballs into roughly 2-ounce rounds, or the size of golf balls. Place these onto your greased roasting tray, inches apart from each other.
Set your meatballs aside in a chilled area and allow them to firm up briefly for roughly 20 minutes.
Once they firm up, roast these until fully cooked and golden brown, roughly 30 minutes. Drain any excess oils and liquids from the roasting tray once done.
Plate your desired amount of pasta and sauce, top with meatballs.