Preheat the oven to 350 degrees F and prepare all ingredients, ensuring the whole kernel corn is well drained.
In a large bowl, lightly whisk the eggs with a fork, then add melted butter and sour cream, mixing well.
Add both the drained whole kernel corn and creamed corn to the bowl and whisk until fully combined.
Pour the corn muffin mix into the wet ingredients and stir gently until the mixture is smooth with no lumps.
Butter an 8x8 inch casserole dish and pour the mixture in, spreading it evenly.
Bake uncovered for 45 minutes until the top is golden, edges slightly cracked, and the center is firm.
Remove the casserole from the oven, let it cool slightly, then serve warm.