Step 1: Preheat and Prepare Preheat your oven to 400°F (200°C). Line a large baking sheet with parchment paper or a silicone baking mat to prevent sticking and make cleanup easier.
Step 2: Combine Meatball Ingredients In a large mixing bowl, combine the ground meat, breadcrumbs, milk, beaten egg, minced onion, garlic, salt, and pepper. Use your hands or a fork to mix everything together until just combined. Be careful not to overwork the meat, as this can make the meatballs tough.
Step 3: Shape the Meatballs Scoop about 1 to 2 tablespoons of the meat mixture and roll it between your palms to form a ball roughly 1 inch in diameter. Place the meatballs on the prepared baking sheet, leaving about an inch of space between each one. You should get about 24 to 30 meatballs.
Step 4: Initial Bake Place the baking sheet in the oven and bake for 15 to 18 minutes, or until the meatballs are cooked through and slightly browned on the outside.
Step 5: Prepare the BBQ Glaze While the meatballs are baking, whisk together the BBQ sauce, brown sugar, apple cider vinegar, and Worcestershire sauce in a small bowl or saucepan. If using a saucepan, simmer over low heat for 5 minutes to thicken the sauce and meld the flavors.
Step 6: Glaze and Finish Once the meatballs are done, remove them from the oven. You can either toss them in a bowl with the sauce or brush the glaze generously over each meatball while they are still on the tray. Return them to the oven for an additional 5 minutes to let the glaze caramelize and become sticky.