Preheat oven to 375℉ (190℃)
Liberally grease muffin tins or line with cupcake liners.
In a medium bowl, combine butter and sugar. Beat in the eggs until blended.
Add in the baking soda and then slowly add the buttermilk while stirring.
Add the cornmeal, flour, and salt. Stir until combined.
Spoon the batter evenly into the muffin tin so that they're ½-⅔ full. Better to err on less to get 12 muffins and go back to even out. (If using the bacon, fill just about ¼ way, add the crumbled bacon, then add the rest of the batter.)
Bake for ~20 minutes until tops brown and a toothpick comes out clean. Depending on your oven, consider turning around half way through the cooking time.