Preheat a 10-inch cast-iron skillet in a 425 degrees F oven. Whisk 3/4 cup each cornmeal and whole-wheat flour, 3/4 teaspoon baking soda and 1/2 teaspoon salt in a bowl. Separately, whisk 1 3/4 cups buttermilk, 2 eggs, 1 tablespoon melted butter and 2 tablespoons honey. Mix the dry ingredients into the wet ingredients. Coat the hot skillet with cooking spray and add the batter. Bake until golden, 18 to 20 minutes.