Preheat oven to 350°F. Grease a 9x13 inch baking dish with butter or non stick spray. This ensures the casserole releases easily after baking and prevents sticking or burning on the edges.

Open canned corn and drain the whole kernel corn well. Leave creamed corn as is. Draining properly helps control moisture and keeps your scalloped corn casserole recipe thick and creamy.

In a large mixing bowl, combine drained corn, creamed corn, sour cream, melted butter, sugar, salt, pepper, and onion powder. Mix gently until everything looks smooth and evenly blended.

Add beaten eggs, corn muffin mix, and cheddar cheese into the bowl. Stir slowly until fully combined. The mixture should be thick, creamy, and slightly textured but not dry.

Pour mixture into prepared baking dish. Spread evenly with a spatula so it bakes uniformly. Tap gently on counter to remove air pockets and level the surface.

Sprinkle crushed crackers evenly on top for a crispy golden crust. Do not press down. Keep topping loose so it bakes into a crunchy, buttery layer.

Bake in preheated oven for 35 to 40 minutes until golden brown and set in the center. Let it rest a few minutes before serving warm and creamy.