Preheat oven to 410°F (210°C)
Add breadcrumbs, grated onion (along with juice), Chicken Bouillon powder, and milk to a large mixing bowl. Mix well and rest it for 8-10 minutes.
Add ground beef, ground pork, grated parmesan cheese, and rest of the ingredients to the bowl. Using a spatula or best with both hands mix everything really well.
Scoop about 1.5 tablespoons of the mixture, place it in between both palms, and roll into smooth balls. Slightly wet your palms in between to prevent the mixture from sticking. Place it on a tray.
Melt butter in a skillet. Once the butter starts to foam, add minced onion and garlic. Saute for 2 minutes until the onion has softened and the raw smell of garlic is no more.
Add chicken stock and simmer for 2-3 minutes. Switch off the flame. Whisk in another tablespoon of butter and chopped parsley.
Arrange the shaped meatball in a single layer. Bake for 12 minutes.
Remove the pan out of the oven and spoon some sauce over the meatballs. Broil for 1-2 minutes more for a golden and crispy top.
Sprinkle chopped parsley on top and serve.