Place the oven rack in the middle position and preheat the oven to 400°F.
Once the oven is preheated, add the butter to a 10-inch cast iron skillet, then place it in the oven and heat until it’s melted, about 10 minutes.
Whisk together the cornmeal mix, sugar, and salt in a medium bowl. Stir in the chopped bacon and cracklings.
In a large measuring cup or another medium bowl, whisk together the eggs and buttermilk until well combined. Then stir the wet ingredients into the dry ingredients.
Once the butter is melted and hot, remove the pan from the oven, carefully swirl the butter around the bottom and sides of the pan, then pour the remaining butter into the batter. Stir the butter in, then pour it into the hot skillet.
Return the cornbread to the oven and bake until the top is light golden brown and an inserted toothpick comes out mostly clean, about 20-22 minutes. Do not overbake.
Remove the cornbread from the oven and let it cool for 10 minutes in the pan. Then carefully release from the pan, cut into slices or squares, and serve warm or room temperature.