Whisk the egg, sour cream, butter and salt together in a large bowl then add the sweet corn and cream style corn and stir once again.
Stir in the corn muffin mix then pour the batter into an 8x8-inch baking pan and bake for 35 to 45 minutes or until a toothpick comes out clean when inserted into the center of the casserole.
Serve with freshly minced parsley for garnish if desired.
Notes
This corn casserole can be stored in an airtight container in the fridge for up to five days.