Preheat oven to 400 degrees.
In medium-sized bowl, combine cornmeal mix, sifted flour, corn muffin mix, sugar (if using), 2 beaten eggs, and buttermilk.
NOTE: Use two small or medium eggs. Or use ONE large egg.
Stir together until batter is smooth. Press large lumps with back of a spoon or fork. Set aside 10 minutes.
Spray muffin tin (6 cups) with vegetable oil cooking spray. Or, grease each cup with 1/2 teaspoon of vegetable oil.
Stir cornbread batter. Fill each cup with batter.
Reduce oven temperature to 375. Bake 20 to 25 minutes or until golden brown and knife inserted in center comes out clean. Muffins will rise with a dome shape.
Serve hot. If desired, slather with salted butter, honey, or maple syrup.