Preheat your oven to 400 degrees F and line a baking sheet with parchment paper for easy cleanup.
In a large bowl, combine ground beef, breadcrumbs, Parmesan cheese, egg, milk, onion, garlic, parsley, salt, pepper, and oregano. Mix until just combined, being careful not to overwork the meat.
Shape the mixture into 1-inch meatballs and place them on the prepared baking sheet, spaced evenly apart.
Bake in the preheated oven for 20 minutes, or until the meatballs are browned and cooked through.
Serve the baked meatballs hot with your favorite sauce or as desired.