Preheat oven to 350°F (175°C). Grease a 9x13 inch baking dish.
In a large bowl, beat softened cream cheese until smooth. Mix in sour cream and cream of chicken soup.
Add garlic powder, onion powder, salt, and pepper. Stir to combine.
Fold in shredded chicken until evenly coated.
Spread mixture in prepared baking dish.
Top with cheddar and mozzarella cheeses.
Mix crushed Ritz crackers with melted butter. Sprinkle over cheese layer.
Bake uncovered for 25-30 minutes until bubbly and golden on top.
Let stand 5-10 minutes before serving.