Preheat the Oven: Preheat the oven to 425°F and place the 10-inch cast iron skillet inside so it can heat thoroughly.
Combine the Dry Ingredients: Add the yellow cornmeal, all-purpose flour, packed light brown sugar, kosher salt, baking powder, and baking soda to a large bowl. Whisk thoroughly until the dry ingredients are evenly combined, then set aside.
Mix the Wet Ingredients: In a separate medium bowl, whisk together the whole buttermilk, honey, and eggs until well combined.
Make the Batter: Pour the wet mixture into the bowl of dry ingredients. Use a rubber spatula to gently mix until just combined, taking care not to overmix, which can make the cornbread tough and dense.
Add the Melted Butter: Pour the 1/2 cup melted butter into the batter and fold it in gently with the rubber spatula until just incorporated, avoiding unnecessary mixing.
Prepare the Hot Skillet: Wearing oven mitts, carefully remove the preheated skillet from the oven. Add the remaining 2 tablespoons of melted butter and use a pastry brush to coat the bottom and sides of the skillet thoroughly.
Fill the Skillet: Pour the prepared batter into the hot, buttered skillet. The batter should visibly sizzle as it contacts the heated skillet. Use an offset spatula to smooth the surface evenly.
Bake the Cornbread: Place the skillet in the oven and bake for about 20–25 minutes, or until the cornbread is set.
Finish and Serve: Remove the baked cornbread from the oven and top with additional butter, if desired. Cut into wedges and serve warm.