Preheat the oven to 375 degrees Fahrenheit. Grease a 12-muffin muffin tin with butter or oil to prevent the cornbread from sticking, and set aside.
Place the melted butter and sugar in a large mixing bowl, and beat together with a whisk until smooth. Add the eggs and buttermilk and whisk to combine.
In a medium bowl, mix together the baking soda, cornmeal, flour, and salt until evenly combined.
Gradually add the dry ingredients into the bowl with the wet ingredients, and stir until just combined and most of the lumps are gone. Don’t over-stir, or the cornbread could become tough due to over-developed gluten.
Divide the batter between the wells of the muffin tin and bake in the oven for about 15-20 minutes, or until the edges are golden brown and a toothpick inserted into the center of a muffin comes out clean.
Remove from the oven and let cook slightly. Run a knife around the edges of the muffins if they’re sticking, and carefully remove from the muffin tin. Enjoy!
The muffins will keep for a few days at room temperature, a week in the refrigerator, or a few months in the freezer.