Preheat the oven to 400°F and ensure a rack is placed in the center position.
Place muffin cup liners in a muffin pan, and then spray the liners lightly with cooking spray.
In a medium bowl, whisk together the dry ingredients: the cornmeal, flour, sugar, baking powder, baking soda and salt.
In a separate small bowl, whisk together the eggs, buttermilk and melted butter.
Combine the wet ingredients with the dry ingredients, let set for one minute before scooping it into muffin cups and baking for 12-15 minutes. The muffins are done when a toothpick inserted comes out clean. Serve immediately with extra butter.
