Preheat oven to 375 degrees F. Spray cooking spray in a 8x8 square baking dish.
In a medium size pan, melt butter over medium-high heat. Once melted, remove from heat and stir in sugar with a whisk.
Quickly add eggs and whisk until blended.
In a glass measuring cup (or bowl), add buttermilk and baking soda; whisk to combine.
Add buttermilk to pan and whisk together. Add all-purpose flour, cornmeal and salt to the pan. Whisk all ingredients together until few lumps remain.
Pour batter into the prepared baking dish.
Bake for 30-40 minutes, or until a toothpick inserted in the center comes out clean.