Irish Teacake

In a bowl, combine the currants, tea, and sugar and leave to soak overnight. Preheat the oven to 350 degrees F. Butter a 9 by 4 by 3-inch baking pan and line with parchment or waxed (greaseproof) paper. Stir the flour and egg into the currant mixture and pour into the prepared pan. Bake for 1 1/2 hours, or until a skewer inserted in the middle of the cake comes out clean. Allow the cake to cool in the pan for 10 minutes before turning out onto a wire rack to cool completely. Serve the cake sliced and spread with butter.(optional)