In a large mixing bowl, cream butter and sugar together.
Add egg. Add the water to the molasses, stir to combine, then stir molasses water into the butter mixture.
Stir dry ingredients together, add to liquid mixture, and combine until smooth. Pour into prepared pan, bake 45 minutes, or until knife inserted in center comes out clean.
To decorate-.
Once cool, split the cake in half horizontally.
Sit the two halves, cut side up, on the counter, and spread one half with jam and the other half with chocolate ganache.
Sandwich the two halves back together.
Ice the entire cake with chocolate ganache, decorate and serve!