Preheat oven to 180°C (356°F) with top and bottom heat.
In a bowl, combine the beef, grated onions, egg, breadcrumbs, salt, cumin powder, pepper, paprika powder, allspice powder, and parsley. Knead until well combined.
Form the mixture into 8-10 egg-sized round meatballs.
Place meatballs on a baking sheet lined with parchment paper.
Press a small recess into the top of each meatball with your finger to form a bowl shape with a raised edge.
Add pea-sized flakes of butter evenly into each bowl.
Bake for 25 minutes at 180°C (356°F) until cooked through.