Preheat the oven to 350 degrees F. Line a large rimmed baking sheet (or two) with parchment paper or foil for easier clean up.
In a large mixing bowl combine the ground beef, milk, breadcrumbs, eggs, chopped Italian parsley, mayonnaise, garlic powder, mayonnaise, salt and black pepper. Mix together just until combined (overmixing can cause the meatballs to be tough).
Scoop the meatball mixture into 1 1/4-inch diameter meatballs (using a #60 cookie scoop or a spoon) and roll gently into a smooth ball. Place meatballs on the prepared cookie sheet in a single layer.
Bake the meatballs for 20 minutes. While they are baking make the Chipotle Sauce.
In a large Dutch oven over medium-high heat, heat the olive oil.
Sauté the onions until translucent. Add the garlic and sauté one additional minute. Remove from heat.
Add the onions and garlic to a blender along with the tomato sauce, salt and chipotle peppers en adobo. Blend until smooth.
Add the sauce back to the Dutch oven, cover and bring to a simmer over low heat. Add the semi cooked meatballs, toss to coat with sauce.
Simmer for 30 minutes covered. Meatballs should reach an internal temperature of 160 degrees F as measured with an instant-read thermometer.
Serve meatballs with pasta or rice. Leftover meatballs are great for meatball sub sandwiches too!
How to Freeze Uncooked MeatballsThis is a great recipe for freezing the meatballs before cooking them!
Prepare the meatballs are directed (the meat mixture and meatballs only).
Place them on a parchment lined baking sheet with some space in between them.
Put the tray in the freezer and allow the meatballs to freeze solid.
When frozen remove the baking sheet and place the frozen meatballs in a freezer bag or freezer container for 1-2 months.
When ready to cook them allow them to thaw in the refrigerator and proceed with the recipe.
How to StoreStore any leftovers in an airtight container in the refrigerator for up to 4 days. Reheat in a saucepan on the stove top or in the microwave.