Preheat oven to 300°F (149°C). Toast pecans for 7–8 minutes. Cool completely.
Increase oven to 350°F (177°C). Grease three 8-inch cake pans, line with parchment paper.
In a large bowl, whisk flour, baking powder, baking soda, cinnamon, allspice, and salt.
In another bowl, whisk bananas, pineapple, eggs, oil, sugars, and vanilla. Combine with dry ingredients. Fold in 1 ½ cups pecans.
Divide batter into pans and bake for 26–29 minutes. Cool completely.
For frosting, beat cream cheese and butter until smooth. Add confectioners’ sugar, vanilla, and salt. Beat until creamy.
Layer and frost the cakes. Garnish with remaining pecans. Refrigerate 15–20 minutes before slicing.
