Cream together the butter and the sugar until light and fluffy. Gradually blend in the custard powder and the flour. Using an icing bag fitted with a large star nozzle, pipe out 20 fingers, well apart, on to greased baking sheets. Bake at 350 degrees F., 180 degrees C., Gas Mark 4, for 20 minutes. Leave to cool on a wire rack. Melt the chocolate in a bowl over a pan of hot water. Dip both ends of the Viennese Fingers into the melted chocolate and leave until set. ----