Instructions

To make the cake: Heat the oven to 350 degrees. Butter three 9-inch round cake pans.

In a blender or food processor, combine the bananas, pineapple, oil and vanilla. Blend until smooth.

In a medium bowl, whisk together the flour, cinnamon, baking soda and salt.

In a large bowl, whisk together the sugars and the eggs until smooth. Whisk in the banana mixture until evenly combined. Whisk in the flour mixture just until you can no longer see dry spots of flour. Divide between the prepared pans and bake until golden brown and a toothpick inserted in the center comes out clean, 25 to 30 minutes. 

Let cool in the cake pans for about 10 minutes, then carefully flip the cakes out onto wire racks to cool completely.

While the cakes cool, make the frosting: Using a stand mixer fitted with the paddle attachment, beat the mascarpone until smooth, then beat in the sugar until light, fluffy and spreadable. Beat in the chopped pecans and vanilla until combined.

When the cakes are cool, place one layer on a serving platter. Top with frosting, followed by a second layer. Repeat with the remaining cake. Frost the top and sides of the cake with the remaining frosting and garnish with the remaining pecans. Serve.