01 -
Preheat oven to 400°F and position oven rack at the lowest level.
02 -
In a large bowl, whisk together all-purpose flour, cake flour, granulated sugar, baking soda, cream of tartar, and salt until evenly blended.
03 -
Add softened unsalted butter to dry ingredients and work it in using hands or a pastry blender until mixture resembles coarse crumbs.
04 -
Pour in buttermilk gradually, stirring just until dough holds together without streaks of flour. If dough is too dry, add 1 to 2 tablespoons more buttermilk.
05 -
Turn dough onto a lightly floured surface and gently shape into a rough 6-inch round mound without overworking.
06 -
Transfer dough to a cast iron skillet and score a cross on the top about ¾ to 1 inch deep using a serrated knife.
07 -
Bake for 35 to 40 minutes until crust is dark golden brown.
08 -
Remove bread from oven and brush the top with melted unsalted butter. Transfer to a rack and allow to cool for 30 to 45 minutes before slicing.