FOR CAKE:
Preheat oven to 350°.
Grease three 9-inch round cake pans with butter; dust the bottom and sides with flour.
Set aside.
Combine flour, sugar, baking soda, cinnamon and salt in a large bowl and stir until well blended.
Add the eggs and oil, and stir until the dry ingredients are moistened, taking care not to beat them.
Stir in the pineapple and juice, 1 cup of the nuts, the bananas and vanilla.
Divide batter evenly among the prepared pans.
Bake until a toothpick inserted into the center of the cakes comes out clean, about 25-30 minutes.
Let the cakes cool in the pans for about 10 minutes, then turn them out onto racks to cool completely.
Spread the icing between the layers, stacking them on a cake plate.
Use toothpicks to keep together.
Ice the top and sides of cake, and sprinkle remaining nuts over the top.
Refrigerate until ready to serve.
FOR CUPCAKES:
If making cupcakes, line 26 regular sized muffin tins with paper liners.
Follow process above to combine ingredients for batter.
Spoon batter almost to the top of each muffin liner.
Bake at 350° for 20-25 minutes, until a toothpick inserted in center comes out clean.
Cool completely before adding icing.
Pipe icing over top of each cupcake.
Sprinkle cupcakes with reserved, finely diced walnuts.
Refrigerate before serving.