Combine banana and shortening in a medium mixing bowl; beat at high speed of an electric mixer 2 minutes. Add egg, and beat 1 minute.
Sift together flour, sugar, baking powder, soda, salt, and spices in a small mixing bowl; add to banana mixture, stirring well. Stir in milk and pecans.
Pour batter into a lightly greased 13- x 9- x 2-inch baking pan; bake at 350° for 20 to 25 minutes or until a wooden pick inserted in center comes out clean. Spread with Lemon Frosting while warm; cool completely. Cut into 2- x 1 1/2-inch bars to serve.