Preheat your oven to 350 degrees Fahrenheit. Line the bottoms of two 9-inch round cake pans with parchment paper and lightly spray the sides with nonstick cooking spray.

In a large bowl, whisk together the flour, baking soda, salt, cinnamon, and nutmeg until well combined and there are no lumps.

In a medium bowl, whisk together the sugar and vegetable oil until combined. Add the eggs one at a time, whisking after each addition until incorporated. Stir in the vanilla extract.

Fold the crushed pineapple with its juice, mashed banana, and chopped pecans into the wet mixture using a rubber spatula or wooden spoon until just combined.

Pour the fruit mixture into the bowl with the dry ingredients and fold gently with a rubber spatula until just barely combined.

Divide the batter evenly between the prepared pans, smoothing the tops with a spatula.

Bake for 30 to 35 minutes, until a toothpick inserted in the center comes out with only a few moist crumbs.

Let the cakes cool in the pans for 10 minutes, then run a thin knife around the edges, invert onto wire cooling racks, and cool completely before frosting, at least 1 to 2 hours.

Beat the softened butter and cream cheese together in a clean bowl using an electric mixer until light and fluffy, about 2 to 3 minutes. Add the powdered sugar gradually, beating on low speed, then increase to medium speed and beat until smooth and creamy.

Place one cake layer on a serving plate or cake board. Spread about 1/2 cup of frosting over the top.

Set the second layer on top and frost the top and sides with the remaining frosting.