Cream together the butter and sugar until light and fluffy.
Beat in the egg and molasses until smooth.
In a separate bowl, whisk together the flour, baking soda, cinnamon, ginger, cloves, and salt. Add to the wet mixture and mix, then stir in the hot water until the batter is smooth (it will be thin, and that is normal).
Pour the batter into a greased 9x13 inch pan and bake at 350F until a toothpick inserted in the center comes out clean, about 45 minutes.
While the cake bakes, combine the sugar, butter, and heavy cream in a saucepan and bring to a boil, stirring constantly. Boil for 2 to 3 minutes, then remove from heat and stir in the vanilla extract.
Slice the warm cake and serve topped with sliced bananas, a generous pour of the warm vanilla cream sauce, and whipped cream.