Classic Irish Soda Bread

1. Adjust oven rack to middle position and heat oven to 400 degrees. Whisk all-purpose flour, cake flour, sugar, baking soda, cream of tartar, and salt together in large bowl. Add softened butter and use fingers to rub it into flour until completely incorporated. Make well in center of flour mixture and add 1-1⁄2 cups buttermilk. Work buttermilk into flour mixture using fork until dough comes together in large clumps and there is no dry flour in bottom of bowl, adding up to 1⁄4 cup more buttermilk, 1 tablespoon at a time, until all loose flour is just moistened. Turn dough onto lightly floured counter and pat together to form 6-inch round; dough will be scrappy and uneven.
2. Place dough in 12-inch cast-iron skillet. Score deep cross, about 5 inches long and 3⁄4 inch deep, on top of loaf and place in oven. Bake until nicely browned and knife inserted in center of loaf comes out clean, 40 to 45 minutes. Remove from oven and brush with melted butter. Let cool at least 30 minutes before serving.

WHOLE WHEAT SODA BREAD
This variation is known as brown bread in Ireland. The dough will be sticky and you may need to add a small amount of flour as you mix it.
Reduce all-purpose flour to 1-1⁄2 cups and cake flour to 1⁄2 cup and increase sugar to 3 tablespoons. Add 1-1⁄2 cups whole wheat flour and 1⁄2 cup toasted wheat germ to dry ingredients.