Combine flour, baking powder, salt, and 1/2 cup white sugar in a medium bowl until well blended. Cut in butter and shortening with a pastry blender until mixture is crumbly. Stir in currants.

Beat egg and milk together in a small measuring cup or bowl. Add to flour mixture and mix gently with a fork just until blended. Dough should have the consistency of pastry dough.

Roll dough on a lightly floured surface to 1/4-inch thickness. Cut with a floured 3-inch round cutter.

Heat a lightly greased griddle or large heavy skillet over medium heat until a few drops of water sizzle on the surface. Cook cakes in batches until golden brown, about 3 minutes. Turn and cook until golden brown on the other side, about 3 minutes more. Transfer to a wire rack. Sprinkle with remaining sugar and serve!