Preheat oven to 375 degrees. Grease and flour a 9-inch round baking pan.
In a large mixing bowl, combine flour, sugar, baking soda, baking powder and salt. Cut in butter with a pastry blender or fork, until mixture resembles coarse meal. Stir in caraway seeds and raisins or currants.
In a separate bowl, whisk together buttermilk and egg whites, stir into flour mixture until moistened.
Turn out onto a well floured surface and knead lightly until smooth. Shape dough into a ball and place in prepared pan. Using a sharp serrated knife, slice an “X” across the top, edge to edge, about 1/2 inch deep. Brush the top with milk.
Bake for 1 hour or until golden brown. Cool in pan on a baking rack. Serve warm with butter.