Place a 10-inch cast iron skillet in the oven and preheat to 425°F.
Option 1: Melt the butter. Place the 8 tablespoons of butter in a microwave-safe bowl and heat in 30-second intervals, stirring in between, until fully melted. Set aside to cool slightly.
8 + 1 tablespoons unsalted butter
Option 2: Brown the butter. In a stainless steel skillet over medium heat, melt the 8 tablespoons of butter. Continue to cook, stirring frequently, until it turns golden brown with a nutty aroma. Be vigilant to prevent burning. As soon as you see the milk solids change to a toasty brown color, remove the pan from the heat and pour the butter into a heat-proof bowl to prevent it from burning. Set aside to cool slightly.
8 + 1 tablespoons unsalted butter
In a large mixing bowl, combine the cornmeal, all-purpose flour, granulated sugar, baking powder, baking soda, and kosher salt.
1 ¼ cups (150 grams) cornmeal, ¾ cup (90 grams) all-purpose flour, ¼ cup granulated sugar, 2 teaspoons baking powder, ½ teaspoon baking soda, 1 teaspoon kosher salt
In a separate bowl, whisk together the eggs, buttermilk, and melted (or browned) butter.
1 ½ cups buttermilk, 2 large eggs, 8 + 1 tablespoons unsalted butter
Pour the wet ingredients into the dry ingredients. Gently stir until just combined. Do not overmix; a few lumps are okay.
Reduce the oven temperature to 375℉ and carefully remove the hot cast iron skillet from the oven. Add the remaining 1 tablespoon of butter to the skillet and let it melt, ensuring the bottom and sides are well coated.
8 + 1 tablespoons unsalted butter
Pour the cornbread batter into the hot, buttered skillet. It should sizzle slightly.
Place the skillet back into the oven. Bake for 20-25 minutes, or until the cornbread is golden brown on top and a toothpick inserted into the center comes out clean or with a few moist crumbs.
Allow the cornbread to cool for a few minutes before slicing. Serve warm, and enjoy!