- Preheat the oven to 375°F (190°C). Lightly grease a baking dish. 
- In a large bowl, mix cream cheese, mayonnaise, and sour cream until smooth. 
- Stir in ¾ cup cheddar cheese, Parmesan cheese, Old Bay seasoning, garlic powder, and hot sauce. 
- Gently fold in crab meat and green onions. 
- Transfer the mixture to the baking dish and top with the remaining cheddar cheese. 
- Bake for 20-25 minutes, until bubbly and golden. 
- Garnish with extra green onions and Old Bay seasoning. Serve warm.