Position rack in middle of oven, and heat oven to 375˚F. In large bowl, whisk together cornmeal, flour, sugar, baking powder, salt and baking soda. Add eggs and buttermilk, and whisk until combined. Stir in creamed corn. Add butter to 10-inch cast-iron skillet, and place in oven. When butter is melted and sizzling, pour about ¾ of it into cornmeal batter and stir until combined. (Leave remaining butter in skillet.) Batter will start to look smooth when melted butter is fully incorporated. Pour batter into hot skillet. Melted butter may form ring around batter, which will ensure browned crust. Bake until cornbread is browned around edges and toothpick inserted in center comes out clean, 20–25 minutes. Remove from oven and serve hot with slather of butter.