Preheat the oven to 400°F.
Mix paprika, oregano, sumac, salt, and pepper in a small bowl.
In a large baking dish, put garlic, onion, olives, and potatoes. Drizzle 2 tablespoons of olive oil on top, followed by ⅓ of the seasoning mixture. Mix until the veggies are well-coated.
Add the chicken drumsticks, remaining oil, and seasonings. Mix until the chicken is completely coated.
Arrange everything in a single layer, nestling the chicken between the veggies. Evenly place lemon slices over the ingredients.
Cover the baking dish with aluminum foil and bake for 55-60 minutes or until the internal temperature of the chicken reaches 170°F.
Remove the foil and place the baking dish under the broiler for 5 minutes, or just until the skin crisps up. Be careful not to let it burn!
Let it rest for 5 minutes, garnish with fresh parsley, and enjoy your delicious meal!