Preheat oven to 375°F. Coat 4- cup oven-safe dish with non-stick cooking spray.
In medium mixing bowl, blend cream cheese, sour cream, 2 TBSP parmesan cheese, 1 TBSP parsley, garlic powder, onion powder, pepper and Old Bay seasoning. Fold in shrimp until well combined. Spread mixture into bottom of prepared dish, smooth the top. Sprinkle remaining 2 TBSP parmesan cheese over the top.
Bake for 20 to 25 minutes, until dip is bubbling around the edges. Turn on oven broiler and broil on High 1 to 2 minutes until parmesan cheese is golden brown. Remove from oven and garnish with remaining parsley. Serve hot with pita chips.