Preheat oven to 350°F. Grease a 13 x 9-inch baking dish; set aside.
Place corn muffin mix, (or homemade Jiffy cake mix) eggs, water, milk, and butter in a large bowl. Use an electric mixer to combine all of the ingredients until smooth.
Pour the batter into the prepared pan.
Bake for 30-35 minutes, or until a toothpick inserted in the center of the cornbread comes out clean.