Pre-heat oven to 400 degrees.
In a small pan over medium heat, add butter and sauté onion for 4-5 minutes until soft. Add minced garlic and cook for another minute. Take off the heat and let cool while you work on meatballs.
To a large bowl add breadcrumbs and milk. Mix and let it sit for 5 minutes. After 5 minutes, add in the rest of the ingredients including the onions and garlic. Mix till combined. Be careful not to over mix as this will make the meat tough.
Line a large baking sheet with foil. Lightly spray with non-stick cooking spray. Scope out 2 Tbsp worth of meat and roll into a ball. Place on the baking sheet, 1 in apart. This will make about 28 meatballs.
Bake for 16-18 minutes or until the internal temperature reaches 165 degrees.
Let them cool for 5 minutes before removing from baking sheet.