Preheat oven to 350°. In a large bowl, whisk flour, sugar, baking powder and salt. In a small bowl, whisk egg, milk and butter. Stir into dry ingredients just until moistened. Fold in raisins and, if desired, caraway seeds.
Transfer to a greased 9-in. square baking pan. Bake until a toothpick inserted in the center comes out clean, 40-45 minutes. Remove from pan onto a wire rack. Serve warm.