Preheat oven to 350F. Grease and flour three 8" cake rounds and line with parchment.
In a large bowl, sift flour, baking soda, sugars, spices, and salt. Whisk until well combined. Set aside.
In a large bowl, combine bananas, pineapple, oil, eggs,vanilla. Whisk until well combined.
Gently fold dry ingredients into wet. Fold in chopped pecans. Batter will be quite thick.
Spread batter evenly among the pans and bake for 30-35 mins or until a toothpick inserted into the center comes out mostly clean and the middle of the cake springs back when pressed.
Remove from oven. Place cakes on wire rack to cool for 10 mins then turn out onto wire rack. Allow cakes to cool completely.
Cream Cheese Frosting:
Using a stand mixer or hand mixer beat butter until pale and creamy.
Reduce speed to low. Add powdered sugar 1 cup at a time and mix on low until well blended. Increase speed to medium and beat for 3 minutes. Add vanilla and salt and continue to beat on medium for 1 minute.
Slowly add chilled cream cheese one cube at a time (about 1 tablespoon at a time). Beat well until blended and ensure no lumps of cream cheese remain.
If needed, add cornstarch or meringue powder 1 tablespoon at a time to stiffen the frosting (I didn't but this is an option).
Run mixer on low for a couple of minutes to remove any air bubbles.
Place one layer of cake on a cake stand or serving plate. Top with about 1 cup of buttercream, spread evenly. Repeat with remaining layers and apply a thin coat of frosting all over the cake to crumb coat. Chill for 20mins.
Frost the cake with a rustic pattern using the remaining buttercream. Sprinkle chopped pecans around the top (or along the bottom) and top with fresh pineapple and banana slices if desired.