In a heavy, large skillet heat caraway seed over medium-low heat for 3 to 5 minutes or until toasted, shaking skillet occasionally to prevent seeds from burning. Remove seeds from skillet; set skillet aside to cool. In a large bowl combine toasted seeds, all-purpose flour, rye flour, baking powder, salt, and baking soda. Using a pastry blender, cut butter into flour mixture until mixture resembles coarse crumbs. Make a well in the center of dry mixture. Using a fork, stir in buttermilk just until moistened.
Turn the dough out onto a well-floured surface. Quickly knead for 10 to 12 strokes until dough is nearly smooth. Roll or pat dough into a circle about 7 inches in diameter and 3/4 inch thick. Cut into 8 wedges.
Coat the cool skillet with nonstick cooking spray. Heat skillet over medium-low heat for 1 to 3 minutes or until a drop of water sizzles. Carefully place the dough wedges in the pan.
Cover and cook about 20 minutes or until golden brown and a wooden toothpick inserted into the side of a wedge comes out clean, turning wedges several times to brown both sides. Sides may still look moist. Check bottoms occasionally and decrease heat, if necessary, to prevent overbrowning. Serve bread warm or at room temperature.