Soft Ginger Cake

This recipe was labelled as coming from grandma's mother-in-law. She also put a note on the bottom of the recipe that this cake was very good.

1 cup sugar
1 cup shortening
1 egg
1 cup molasses
1 cup boiling water
2 tsp. soda
1 tsp. ginger
3 cups sifted flour (may take a bit less)