Preheat the oven to 350°F. Place two tablespoons of the butter in a 9-inch cast iron skillet and set aside.
Melt the remaining two tablespoons of butter in a microwave safe bowl and set aside.
In a medium mixing bowl, stir together the buttermilk, vegetable oil, eggs, and the two tablespoons of melted butter.
In a large mixing bowl, whisk together cornmeal, flour, sugar, baking powder, and salt.
Make a well in the center of the dry ingredients. Pour the wet ingredients into the well and stir, just to moisten the dry ingredients - the batter will be lumpy.
Place the cast iron skillet with butter over medium-high heat on the stovetop. When butter is melted, pour the cornbread batter into the skillet. As the melted butter comes up the sides of the batter, gently use a spoon or spatula to spread it over the top of the batter.
Place the skillet in the preheated oven and bake for about 25 minutes, or until a toothpick inserted in the center of the cornbread comes out with a few moist crumbs. The center should be just set.
Remove skillet cornbread from the oven, slice, and serve warm.
Notes
Store in an airtight container on the counter or in the refrigerator for 3-4 days, or wrap well and freeze for up to 1 month.
For tender, soft cornbread, do not overmix the batter. Lumps in the batter are fine.This is a soft, thick, cake-like cornbread. It is sweet and delicious, without any grittiness. Batter can also be baked in an 8-inch square baking dish for about 25 minutes. Use the two tablespoons of butter to grease the baking dish and put the remaining butter into the batter along with the rest of the melted butter.Skillet cornbread is fun to serve straight out of the skillet. If you are not cutting and serving it right away, I recommend removing it from the cast iron skillet. Cast iron holds heat for a long time and the cornbread will continue cooking (may dry out) if you leave it to sit in the skillet after it comes out of the oven.