In a small bowl soak the ½ cup panko breadcrumbs in the ½ cup milk. The breadcrumbs will absorb the milk and become soggy.
In a food processor pulse the ½ cup parmesan cheese, ½ cup fresh parsley, 1 large onion , and 3 cloves of garlic until finely chopped.
Add the breadcrumb/milk mixture, onion mixture, 1 pound of ground beef, 1 pound of ground mild Italian sausage, 2 large eggs, 1 teaspoon kosher salt, 1 teaspoon black pepper, 1 teaspoon Worcestershire sauce, ½ teaspoon dried basil, and ½ teaspoon dried oregano to a large bowl. Mix with your hands until just combined.
Shape the mixture into one-inch meatballs using approximately 2 tablespoons of the mixture for each meatball. When shaping the meatballs keep them loose. Rolling and squeezing them into tight balls will create tough overworked meatballs. Place the meatballs on a foil-lined baking sheet.
Bake for 18-20 minutes. Meatballs are done when they reach an internal temperature of 165°F (74°C). You can also cut a meatball in half to make sure the meat is no longer pink.
Notes
Do not overwork the meatballs. Mixing the ingredients by hand allows you to ensure the ingredients are combined completely without overworking the mixture. Overworking the mixture creates tight tough meatballs.To test and adjust the seasoning, microwave a small amount of the meatball mixture until it is fully cooked. Taste and adjust seasoning if necessary.When rolling the meatballs, lightly oil your hands to keep the meatball mixture from sticking to your hands.Shape into evenly sized meatballs so that they all cook at the same rate.Storage: Store leftover meatballs in an air-tight container in the refrigerator for up to 5 days. Reheat over low heat in a saucepan or the microwave.