Step 1Combine unbleached flour, whole-wheat flour, baking powder, baking soda, brown sugar, granulated sugar, salt, cinnamon and caraway seeds. Cut butter into dry ingredients by hand or using paddle or hook attachment on mixer at slow speed.
Step 2Add eggs and buttermilk to form a soft dough. Stir in raisins. Turn out onto floured work surface and gently knead 8 times or so to firm up dough. Let rest 10 minutes.
Step 3Shape into an 8- or 9-inch round. Score top with a knife to make cross. Dust with white flour or sprinkle with bran or oatmeal. Place in 9-inch cast-iron pan and bake until top is brown and toothpick inserted in center comes out clean, 40 to 50 minutes. Remove and cool in pan on rack.