Stir together flour, gingerroot or ground ginger, finely shredded orange peel, cinnamon, baking powder, and baking soda in a medium mixing bowl. Set aside.
Beat together butter and brown sugar in a large mixing bowl with an electric mixer on medium to high speed until combined. Add egg and beat well. Beat in pumpkin and molasses on medium speed until smooth.
Alternately add flour mixture and milk to the pumpkin mixture, beating until smooth. Pour into a greased and lightly floured 8x8x2-inch baking pan.
Bake in a 350 degree F oven for 35 to 40 minutes or until a wooden toothpick inserted near center comes out clean. Cool in pan on a wire rack 10 minutes. Serve warm with whipped cream. If desired, garnish with orange peel curls. Makes 9 servings.