In a large bowl, cream butter and sugar until light and fluffy. add egg; beat well. Beat in molasses. Combine the flour, baking soda, spices and salt; add to the creamed mixture alternately with water, beating well after each addition.
Transfer to an ungreased 13x9 baking pan; sprinkle with brown sugar. In a microwave, heat water and butter until butter is melted; carefully pour mixture over batter.
Bake at 350* for 35 to 40 minutes or till a toothpick inserted near center comes out clean. Serve warm. Garnish with whipped cream and cinnamon if desired.