In a med. saucepan, measure 1 cup water and 3/4 cup raisins. Bring this mixture to a slow boil over medium heat. Turn the heat to low, and let simmer gently for about 10 minutes. (I watch until the liquid has reduced to about 1/2 cup measure)
Let this cool.
Cream the sugar and the shortening or butter until light & fluffy. Add the egg and the vanilla and mix well. Add the dry ingredients alternately with the reserved 1/2 cup liquid from the raisins. Bake at 350 degrees for 15 to 20 minutes or until done in the center. Use a toothpick, and poke it down in the center of the cake. If it comes out clean, the bars are ready. Cool on a wire rack, then glaze.
For the Vanilla Glaze: Heat butter in saucepan until melted, or melt butter in microwave. Stir in powdered sugar and vanilla. Stir in water, cream or milk, 1 tablespoon at a time, until glaze is of desired consistency.