Preheat oven to 350°F.
In a large mixing bowl, cream together sugar and butter using electric beaters. Once the mixture is light and fluffy add in molasses and eggs.
Heat water in a small saucepan over medium heat; water should be very hot but not boiling.
Sift all dry ingredients, and add to wet mixture. Mix until smooth. Add water to the mixture; stir to combine.
Pour mixture into a greased 9-inch cake pan; bake for about an hour or until a cake tester comes out clean.
For the toffee sauce, bring sugar, cream and butter to boil in a saucepan over medium-high heat. Stir continuously to prevent burning on the bottom. Cook for about 4 minutes, remove from heat and allow to cool. This can be done a few hours ahead of time and held at room temperature.
Remove cake from pan, smother top with toffee mixture and serve warm with vanilla ice cream or unsweetened whipped cream.