Preheat the oven to 350°F. Spread chopped pecans onto a baking sheet in a single layer and toast for 5 minutes.
Prepare a muffin tins with paper cupcake liners and set aside.
In a large bowl, whisk together flour, baking soda, cinnamon, allspice and salt. Set aside.
In another large bowl, whisk together banana, egg, brown sugar, sugar, oil and vanilla until combined. Fold in crushed pineapple.
Add dry ingredients to wet ingredients and stir to combine. Fold in ¾ cup pecans (the remaining ¼ cup will be for garnish).
Fill cupcake liners ⅔ full and bake for 20 minutes, or until toothpick inserted into the center comes out with only moist crumbs.
Let cool in pan for 10 minutes and then transfer to wire rack to cool completely.
While the cupcakes cool, make the frosting! In a medium bowl, beat cream cheese and butter on high speed until smooth and creamy.
Add powdered sugar, vanilla, lemon juice and salt and beat to combine on low speed, then bump it up to high speed until smooth with soft peaks. Add milk or more powdered sugar if necessary for desired consistency.
Once cupcakes have completely cooled, either fit a piping bag with desired tip and fill with frosting or use a spatula to frost each cupcake. Top with toasted pecans and enjoy!