Spray the 12" Large Skillet with non-stick cooking spray and set aside.
Whisk together the cornmeal, flour, sugar, baking powder, salt, and baking soda in a large bowl.
Whisk together the buttermilk and eggs in another bowl.
Whisk the buttermilk mixture into the cornmeal mixture until just blended.
Fold in the butter and scrape the batter into the prepared skillet.
Smooth the batter out to the edges of the pan.
Cover the pan and cook over low heat until the cornbread has risen and a few moist crumbs cling to a cake tester, about 30 minutes.
Serve warm or at room temperature.