Preheat oven to 350 and line cupcake pans with paper.
Measure all the dry ingredients into a bowl.
Mash the bananas and pineapple with a potato masher in another bowl.
In your largest bowl, cream butter and sugar with a mixer.
Beat in eggs and vanilla, then stir in the bananas and pineapple.
Combine the dry ingredients with the wet.
Fold in the coconut and walnuts
Transfer to cupcake pans; fill them between 1/2 and 3/4 full.
Bake 20 - 25 minutes
Cool a few minutes in the pan, then remove to a rack to cool completely before icing