Preheat oven to 350 degrees F. Spray or grease the bottom of a 13 x 9 -inch pan. Set aside.
In a large bowl, combine the flour, sugar, spices and salt. Cut in the butter until mixture has the consistency of small peas. Remove 1/2 cup of the mixture to reserve for crumbs.
To the remaining flour mixture, add the egg, buttermilk, banana, soda and molasses. Beat with electric mixer for 2 minutes. Pour into prepared pan.
In a small bowl, mix the reserved flour mixture with the nuts and coconut. Sprinkle on top of cake.
Bake at 350 degrees F for 35-40 minutes, or until toothpick inserted in the center comes out clean.Remove from oven and cool completely on rack.