Preheat oven to 400 degrees. Spray two large baking sheets with cooking spray, or line the baking sheets with silicone baking mats.
In a large bowl, stir together breadcrumbs and milk. Let sit for 5 minutes.
In a small bowl, whisk together eggs. Then, pour over breadcrumbs.
Add sausage, beef, salt, garlic powder, oregano, parsley, and mozzarella to bowl. Stir well so that all ingredients are evenly combined (I often find it easy to do this with my hands).
Form meat into balls about 1.5" in diameter. Place on prepared baking sheets
Bake for 20 minutes, flipping the meatballs halfway through.