Mix together hot water, sugar, salt, shortening; cool to lukewarm. Measure 1/2 cup very warm water into mixing bowl. Sprinkle in yeast; stir until dissolved. Stir in lukewarm water mixture. Add egg, flour, and raisins. Stir until well blended, about 2 minutes.
Let rise in warm place, free from drafts, about 50 minutes or until more than doubled in bulk. Stir down. Beat vigorously about 1/2 minute. Turn into greased 1 1/2 quart casserole. Bake immediately, uncovered in a hot oven at 400 degrees about 45 minutes. While warm spread with the powdered sugar glaze if desired.