Preheat the oven to 375°F.
Grease an 8 x 8-inch baking dish with 1 tablespoon softened butter, coating the bottom and sides evenly.
Set the prepared baking dish aside.
Melt 8 tablespoons salted butter in the microwave on high until fully melted.
Pour the melted butter into a large mixing bowl.
Add the white sugar, brown sugar, and honey to the melted butter.
Whisk until the mixture is smooth and evenly combined.
Measure the buttermilk into a separate cup or small bowl.
Add the baking soda to the buttermilk.
Stir until the baking soda is incorporated into the buttermilk.
Pour the buttermilk mixture into the butter and sugar mixture.
Whisk until fully combined. This step also helps cool the melted butter before the eggs are added.
Crack the eggs into a small bowl or measuring cup to check for shells.
Add the eggs to the batter mixture.
Whisk until the mixture is smooth and fully blended.
Add the cornmeal, all-purpose flour, and salt to the mixing bowl.
Whisk just until the dry ingredients are incorporated and the batter is combined.
Do not overmix the batter, as this may affect the final texture.
Pour the batter into the prepared baking dish.
Spread the batter evenly into all four corners of the pan.
Smooth and level the top with a spatula.
Bake for approximately 30 minutes, or until the cornbread is golden brown and has pulled slightly away from the edges of the pan.
Check for doneness by inserting a toothpick into the center. The toothpick should come out clean or with a few moist crumbs.
Remove the cornbread from the oven.
Allow it to cool slightly before slicing.
Serve warm or at room temperature.