In a large mixing bowl, stir together flour, brown sugar, cinnamon, ginger, baking powder, soda, and allspice. Add shortening, molasses, egg, and 1/2 cup water. Beat with a mixer on low to medium speed until combined. Beat on high speed 2 minutes. Fold in the 1/4 cup crystallized ginger. Pour into a greased and floured 2-quart square baking dish.

Bake in a 350 degree F oven 35 to 40 minutes or until a toothpick inserted near center comes out clean. Cool 10 minutes.

In a medium saucepan combine sugar and cornstarch; add half-and-half or light cream and butter. Cook and stir over medium heat until mixture is bubbly. Reduce heat; cook for 1 minute. Remove from heat. Stir in the 2 tablespoons crystallized ginger, the lemon peel, and lemon juice. Serve warm with gingerbread. Makes 9 servings.