Heat the oven to 350°F and butter a 2 1/2-quart baking dish with 1 teaspoon of the melted butter.
Whisk the sour cream, eggs, remaining melted butter and salt in a large bowl until smooth.
Stir in the corn muffin mix, drained corn and creamed corn just until no dry pockets remain.
Spread the batter in the prepared dish and smooth the top lightly.
Bake for 50 to 55 minutes, until golden around the edges, set to 160°F at the center and still faintly jiggly.
Rest for 10 minutes before serving with a spoon.