Divide the meat mixture into 5 equal portions. Take one portion and flatten it in the palm of your hand. Place a hard-boiled egg in the center and wrap the meat mixture around the egg, forming a large meatball. Make sure the egg is completely encased in the meat mixture. Repeat this process for the remaining portions and eggs, ensuring uniformity in size for even cooking.

Prepare the Baking Dish
Place the thinly sliced onions in the bottom of a baking dish. This not only adds flavor to the meatballs but also prevents them from sticking to the dish, ensuring an easy and clean presentation.

Arrange the Meatballs
Carefully place the stuffed meatballs on top of the sliced onions in the baking dish. Arrange them evenly, leaving enough space between each meatball for proper heat circulation.

Bake the Meatballs
Transfer the baking dish to the preheated oven. Bake the meatballs for about 25-30 minutes, or until they are cooked through and have reached an internal temperature of 160°F (71°C). This temperature ensures that the meat is safe to eat while remaining juicy and flavorful.