Preheat oven to 350°F (180°C). Butter 3 (8-inch) round cake pans. Line bottom of pans with parchment paper.
In a large bowl, sift together flour, sugar, cinnamon, baking soda, salt, and nutmeg; stir in pecans.
In a medium bowl, stir together oil, banana, eggs, and vanilla. Add oil mixture to flour mixture, stirring just until moistened. Fold in pineapple. Divide batter among prepared pans.
Bake until a wooden pick inserted in center comes out clean, 20 to 25 minutes. Let cool in pans for 10 minutes. Remove from pans, and let cool completely on wire racks.
Place a cooled cake layer on a cake plate. Place 1 cup (250 grams) Cream Cheese Frosting in a pastry bag fitted with a ½-inch round piping tip. (Alternatively, cut a ½-inch opening in tip of pastry bag.) Pipe around edge of cake layer. Spread half of Pineapple-Pecan Filling (about 300 grams) on layer inside piped border. Top with second cake layer, and pipe border around edge. Spread remaining Pineapple-Pecan Filling inside piped border. Top with remaining cake layer. Spread a thin layer of Cream Cheese Frosting on top and sides of cake to create a crumb coat. Refrigerate until filling is set, 30 to 45 minutes. Cover and refrigerate remaining frosting.
Using a spatula, fold remaining Cream Cheese Frosting until smooth and workable. Spread frosting on top and lightly on sides of cake. Using a bench scraper, smooth edges until desired amount of frosting is left. Cover and refrigerate for at least 2 hours or up to overnight before serving.
Recipe by Bake from Scratch at https://staging.bakefromscratch.com/december-three-popular-recipes-made-gluten-free/