Preheat the oven to 350°F (180°C). Grease and flour three 9-inch round cake pans.
In a large bowl, combine the flour, sugar, baking soda, cinnamon, and salt.
Stir in the eggs, oil, vanilla, pineapple, bananas, and pecans until well combined.
Divide the batter evenly between the prepared cake pans.
Bake for 25-30 minutes, or until a toothpick inserted into the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes, then remove from the pans and cool completely on wire racks.
For the frosting, beat the butter and cream cheese together in a large bowl until smooth.
Gradually add the powdered sugar and vanilla, beating until smooth.
Spread the frosting between the layers and over the top and sides of the cake. Sprinkle with chopped pecans or walnuts.
Store the cake in the refrigerator until ready to serve.
