Middle Eastern Delight: Beef Kefta Casserole

Ingredients

• 1 tsp kosher salt
• 1/2 tsp ground black pepper
• 2 tsp minced garlic
• 2 tsp allspice
• 1 cup unseasoned tomato sauce
• 1 tbsp chopped flat-leaf parsley, plus extra for garnish
• 1 yellow onion, divided into two parts
• 1 tbsp olive oil, plus extra for greasing the pan
• 2 lbs ground beef
• 1 thinly sliced tomato for garnish