Preheat the oven to 350F (175C). Grease and flour three 8-inch or two 9-inch cake pans.
Sift the flour, sugar, baking powder, baking soda, salt, and cinnamon into a large mixing bowl; add the shortening, buttermilk, and banana. Mix until all the dry ingredients are dampened, then beat at low speed for 2 minutes. Add the eggs and beat for 1 minute.
Divide the batter among the prepared pans and bake for 25 to 30 minutes. Cool for 10 minutes in the pans, then turn out the cakes on a rack to cool completely before frosting.
Combine the cream cheese, butter, confectioners' sugar, and vanilla extract and beat until fluffy. Fold in the pecans, and frost the cake. If you love lots of icing, you can make 1 1/2 times this recipe. Remember, this is not banana bread but a stacked cake, so be sure to frost between the layers as well as the outside.