Preparation:

Step 1: Preheat the oven
Preheat your oven to 350°F (175°C). Grease a 9×13-inch baking dish with cooking spray or butter.

Step 2: Prepare the creamy base
In a large mixing bowl, combine the softened cream cheese, sour cream, melted butter, and milk. Whisk until the mixture is smooth and creamy.

Step 3: Add the corn and seasonings
Stir in the whole kernel corn, creamed corn, garlic powder, onion powder, smoked paprika, and chopped green onions. Mix well to ensure all the corn is coated in the creamy mixture. Season with salt and pepper to taste.

Step 4: Incorporate the cheeses
Fold in 1 cup of shredded cheddar cheese and 1/2 cup of grated Parmesan. Mix until evenly distributed.

Step 5: Assemble the casserole
Pour the mixture into the prepared baking dish, spreading it out evenly.

Step 6: Add the topping
In a small bowl, combine the crushed buttery crackers, 1/2 cup shredded cheddar cheese, and 2 tablespoons of melted butter. Sprinkle this mixture evenly over the top of the casserole.

Step 7: Bake
Place the casserole in the preheated oven and bake for 30-35 minutes, or until the top is golden brown and the edges are bubbly.

Step 8: Rest and serve
Remove the casserole from the oven and let it rest for 5-10 minutes before serving. This allows the creamy filling to set slightly, making it easier to serve.