In a large bowl, cream shortening and sugar until light and fluffy. Beat in egg. Combine the water and molasses. Combine the flour, ginger, baking soda and salt; add to creamed mixture alternately with molasses mixture, beating well after each addition. Pour into a greased 8-in. square baking pan.
Bake at 350° for 28-32 minutes or until a toothpick inserted in the center comes out clean. Serve warm with whipped topping.