Preheat your oven to 350°F (175°C) and grease two 9-inch round cake pans.
In a large bowl, mix the mashed bananas and crushed pineapple until well combined.
In another bowl, whisk together the flour, sugar, baking soda, salt, and cinnamon.
Gradually add the dry ingredients to the banana mixture, mixing gently.
In a separate bowl, beat the eggs and oil together until smooth.
Stir the egg mixture into the banana batter until fully combined.
Fold in the chopped walnuts and vanilla extract.
Pour the batter evenly into the prepared cake pans.
Bake for 30-35 minutes or until a toothpick inserted in the center comes out clean.
Allow the cakes to cool in the pans for 10 minutes before transferring to a wire rack to cool completely.
For the frosting, beat the cream cheese and butter until creamy, then gradually add powdered sugar and vanilla.
Frost the cooled cakes and serve.