Preheat and Prep. Begin by preheating your oven to 350°F. Grease a 9x13-inch baking dish for that perfect casserole shape.
Mix the Goodness. In a large bowl, combine the drained whole kernel corn, cream-style corn, sour cream, melted butter, cornbread mix, shredded cheddar cheese, salt, and black pepper. Stir this delightful mixture until all ingredients are well incorporated.
Casserole Creation. Pour this creamy corn mixture into your prepared baking dish, spreading it evenly to ensure every bite is as delicious as the last.
Bake to Perfection. Slide your casserole into the preheated oven and let it bake for approximately 45 to 50 minutes or until it's golden brown and slightly set in the center. A toothpick inserted into the center should come out mostly clean.
Garnish and Serve. Once your Cheesy Corn Casserole is out of the oven, sprinkle it with freshly chopped parsley for a burst of color and added freshness. Then, slice it into squares and serve warm.