Preheat oven to 350. In a large bowl, begin by whisking cornmeal, flour, sugar, baking powder, salt, vegetable oil, buttermilk ,and eggs together until well blended into a smooth batter. Next, add the butter, and continue to whisk until well blended.
Carefully pour the batter into a (liberally oiled) cast iron pan. Place pan in the preheated oven and cook for 35 to 40 minutes.
Allow the cornbread to rest in the pan for 15 minutes before serving. Butter and serve. Enjoy!