• Preheat the oven to 400°F. Line a rimmed baking sheet with aluminum foil.
• In a large mixing bowl, combine the bread crumbs, milk, Parmesan cheese, Italian seasoning, salt, and pepper. Let the mixture sit for 10 minutes to moisten the bread crumbs.
• Stir in the egg, onion, parsley, and garlic. Add the beef and pork. Shaping your hand like a claw, massage the mixture together, until well combined. (Try not to squeeze the mixture together too much or it can make the meatballs less tender.)
• Divide the mixture into 24 (2-ounce) meatballs.

For the Oven:

• Grease the foil-lined baking sheet with 2 tablespoons of olive oil. Arrange the meatballs 1 inch apart on the sheet. Drizzle the tops with the remaining 2 tablespoons of olive oil.
• Bake for 18 to 20 minutes or until a meat thermometer inserted into the center of each meatball registers 160°F.
• Increase the oven to broil, and broil until the meatballs are browned, about 1 to 3 minutes more. Serve immediately or toss with pasta sauce.

For the Stovetop:

• In a 12-inch skillet over medium heat, add all of the olive oil. When the oil is hot, add meatballs in batches, making sure to not overcrowd the skillet. Cook, turning each meatball about every 1 minute until all sides are browned.
• Once all of the meatballs are browned, reduce the heat to medium-low.
• Cover with a lid and cook until a meat thermometer inserted into the center of each meatball registers 165°F. Serve immediately or toss with pasta sauce.

To Serve with Sauce:

• Place the marinara sauce in a large pot and bring to a simmer over medium-low heat. Once the meatballs are done cooking, add them to the sauce. Cover the pot, leaving the lid slightly vented, and cook at a low simmer, for about 20 to 30 minutes. This flavors the sauce and helps to tenderize the meatballs even further.